Camila Domonoske

The four Americans who were part of a prisoner exchange between the U.S. and Iran have been released by Iran, a senior administration official confirms, and those who wished to depart the country have left.

A fifth American was released separately from the exchange.

The release of the prisoners was the result of "tireless" work by American diplomats, on the sidelines of nuclear negotiations with Iran, President Obama said Sunday.

"I've met with some of the families. I've seen their anguish — how they ached for their husbands and sons," Obama said.

Water contamination in Flint, Mich, — where the city switched water sources, causing pipe corrosion and ultimately filling the city's water supply with high levels of lead — has prompted President Obama to declare a state of emergency.

The move, which was requested by Michigan Gov. Rick Snyder, means FEMA is authorized to provide equipment and resources to the people affected. Federal funding will help cover the cost of providing water, water filters and other items.

Five years ago, Ted Williams became famous. The Columbus Dispatch posted a video of Williams, panhandling on the side of the road, showing off a pitch-perfect announcer's voice.

On Saturday, Iran released four detained Iranian-Americans and the U.S. released or pardoned seven Iranians, and dropped extradition requests for 14 more, in a highly choreographed prisoner exchange. Iran also simultaneously released a fifth American detainee.

Iran is releasing four Iranian-American prisoners Saturday, as part of a prisoner swap with the U.S.

The release, originally reported by Iranian state media, has been confirmed by U.S. officials. Iran is also releasing a fifth American detainee, separate from the exchange.

Tsai Ing-Wen, of Taiwan's pro-independence party, claimed victory in the nation's presidential elections on Saturday night.

With the vote count still underway, Tsai led with 60 percent of the vote, indicating a landslide victory; the ruling Nationalist party conceded defeat.

That makes Tsai the self-governing island's first female president.

An hours-long attack by militants on a luxury hotel in Burkina Faso's capital has left approximately 20 victims dead. An early-morning assault by security forces killed four attackers and freed 126 hostages, officials say.

Among the victims killed was an American, identified by the U.S. State Department as Michael James Riddering, according to Reuters.

The company that owns the leaking natural gas well in Los Angeles understated the number of air samples showing higher-than-usual levels of benzene, The Associated Press reports.

Adding to concerns over the disaster, efforts to stop the leak appear to have destabilized the well, the Los Angeles Times reports, raising the risk of a blowout.

Over the Easter holiday in 2015, millions of dollars worth of cash, gems and jewelry were stolen from a facility where London jewelers stored their wares. The audacious theft — which involved descending through an elevator shaft and drilling through concrete and metal walls — seized the attention of the world.

The Episcopal Church has been disciplined by the Anglican Communion, the international faith fellowship of which the church is a part, over deep disagreements about homosexuality and same-sex marriage.

The church has not been removed from the communion. However, it will be barred from Anglican decision-making for three years and will no longer represent the community in ecumenical or interfaith bodies, the Anglican organization has decided.

The World Health Organization announced Thursday that the Ebola epidemic in West Africa is over — for now.

For the first time since the outbreak began in December 2013, all three of the hardest-hit West African nations — Liberia, Guinea and Sierra Leone — have had zero reported cases of Ebola for 42 days in a row. That's equal to two full incubation cycles of the virus.

Over the past two weeks, the Defense Department has transferred 14 detainees from the Guantanamo Bay detention camp.

That leaves 93 detainees at the military prison in Cuba — the first time the prison's population has been below 100 since it opened in January 2002.

The most recent release was announced Thursday by the Defense Department.

The Internet had many, many responses to actor Sean Penn's account of meeting Joaquin "El Chapo" Guzmán, which was published by Rolling Stone on Saturday: shock, anger, derision, astonishment, utter bafflement ...

But from one quarter, at least, there was pure excitement.

"EL CHAPO GUZMAN WEARING BARABAS SHIRT !" was the all-caps announcement from the clothing company Barabas.

A nuclear-capable B-52 bomber flew over an air base in South Korea in a move that was both a training mission and a show of force.

The low-level flight was conducted as a demonstration of U.S. commitment to South Korea, in response to a nuclear test by North Korea, the U.S. Pacific Command said in a statement.

Germany has started 2016 with a deep and bitter debate: How should the country respond to the New Year's Eve attacks in Cologne, in which mobs of men reportedly robbed and sexually assaulted women on the streets?

Concrete information about the night is sparse, and competing narratives abound.

Doctors Without Borders says a hospital it supports in Yemen was hit by a projectile Sunday morning, leaving at least four people dead and 10 injured.

The medical aid organization, also known as Médecins Sans Frontières or MSF, said more victims might still be trapped in the building's rubble.

Aid is due to arrive in the besieged towns of Madaya, Foa and Kefraya soon — possibly on Monday.

Meanwhile, an airstrike in the Idlib province has killed scores of people, and Syria's government says it will be willing to join peace talks in Geneva with some opposition groups.

One number has everybody's attention this afternoon. But why stop at one?

Here's the prize jackpot, plus a few other lottery stats worth knowing:

$900,000,000

The eye-popping, record-breaking Powerball jackpot value, as of Saturday afternoon. If no one wins tonight, the jackpot could crack a billion.

That's based on a single winner selecting the annuity option, which pays out over three decades. Alternately ...

Seventy-five thousand miles is long enough to cross the United States about 25 times. Long enough to circle the equator — three times.

And for 75 years, 75,000 miles was long enough to be legendary. Or more specifically, it was 75,065 miles — the miles-biked-in-a-year record set by Tommy Godwin in 1939 and never broken since.

Joaquin "El Chapo" Guzmán had seen his name in headlines. He knew it graced the world's Most Wanted lists.

But it appears that the notorious drug kingpin wanted something more: He wanted his name in lights.

It was a memorable name: Thelonious Monk, like the jazz musician.

And when Adam Marton read it, a decade-old memory came flooding back.

Marton is an editor at The Baltimore Sun. He was working on an infographic about the homicides in Baltimore in 2015 — a record 344 deaths, most of them black men, most of them shot to death.

Thelonious Monk was one of those victims. And years before, Marton says, Monk had stolen his car.

The U.S. economy added 292,000 jobs in December while unemployment held steady at 5 percent, according to the latest figures from the Bureau of Labor Statistics.

The number of new jobs was higher than many economists had anticipated; NPR's John Ydstie says experts had expected about 200,000 new jobs.

Three besieged towns in Syria will soon be receiving humanitarian assistance: The Syrian government said Thursday it will allow aid to enter the villages, after multiple organizations reported deaths from starvation.

Bashar Assad's government is permitting aid to Madaya, which has been under siege by the regime since July, as well as Foua and Kfraya, two villages adjacent to each other that have been besieged by anti-government forces for more than a year, the Associated Press reports.

More than two months after a natural gas storage well in Southern California began uncontrollably spewing methane gas, the governor of California has declared a state of emergency.

The legal saga of the monkey selfie continues: On Wednesday, a federal judge said the macaque who famously snapped a picture of himself cannot be declared the owner of the image's copyright.

At least, until Congress says otherwise.

There's "no indication" that the Copyright Act extends to animals, U.S. District Judge William Orrick wrote in a tentative opinion issued Wednesday in federal court in San Francisco.

The chief justice of Alabama's Supreme Court has ordered the state's probate judges not to issue marriage license to same-sex couples — despite a decision by the U.S. Supreme Court last year that legalized same-sex marriage in America.

Roy S. Moore, the chief justice of the state Supreme Court, issued an administrative order Wednesday. He noted that the Supreme Court of Alabama had, in March of 2015, upheld the state's ban on same-sex marriage.

Star Wars: The Force Awakens revolves around the story of staff-wielding scavenger Rey.

(That's hardly a spoiler; she's front-and-center in the movie poster, after all.)

But in the world of Star Wars toys, Rey's been hard to find — and fans took to social media, under the hashtags #WheresRey and #WhereisRey, to complain about all the movie merchandise that left her out.

A hotel in downtown Dubai erupted in flames on Thursday evening, just two hours before the city was due to celebrate New Year's Eve with a massive fireworks display.

At midnight local time, the celebration proceeded as planned — resulting in a jarring double display of light and smoke, as firefighters continued to battle the blaze at one skyscraper while fireworks were sent off from the nearby Burj Khalifa.

Time zone by time zone, the planet is saying goodbye to 2015.

The end of the year is still hours away in the U.S., but Australia has already hailed the new year with fireworks like those (see above) in Sydney Harbour.

In Japan's capital, balloons were released from Tokyo Tower.

A few highlights from other celebrations planned around the globe:

Ethan Couch — the "affluenza teen" who killed four people while driving drunk two years ago and recently fled to Mexico with his mother — has been granted a temporary stay against his extradition to the U.S. His mother was deported to Los Angeles on Wednesday evening.

Couch and his mother were detained in Mexico on Monday. They originally had been scheduled to return to the U.S. on Wednesday, where Ethan Couch would face a hearing before a juvenile court judge.

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