Samantha Raphelson

Updated on Sunday at 10:00 a.m. ET

Hundreds of thousands of students, teachers, parents and victims rallied in Washington, D.C., and across the country on Saturday to demand tougher gun control measures, part of a wave of political activism among students and others impacted by school shootings.

The brand-new Olympic stadium in Pyeongchang, South Korea, will be used just four times before it's decommissioned after the Winter Olympics and Paralympics. The venue will be used for opening and closing ceremonies for two Olympics, and then it will be demolished.

Lawmakers in the United Kingdom are debating a new tax on disposable cups in an effort to cut down on waste.

While the so-called "latte levy" is controversial, the goal is to replicate the success of Britain's tax on plastic bags; their use has declined by 80 percent since the tax was introduced in 2015. Proponents of the tax say it would encourage people to carry around their own reusable cups rather than use disposable ones, which in their current form are difficult to recycle.

Homeless shelters across the country are being strained by frigid weather and a population of people who are homeless that is up for the first time since 2010, according to the U.S. Department of Housing and Urban Development.

Palestinian Christians attacked the convoy of the Greek Orthodox Patriarch of Jerusalem during a visit to Israeli-occupied West Bank on Saturday to protest the church's controversial property sales to Jewish and Israeli buyers.

The number of migrants who died crossing the Mediterranean Sea surpassed 3,000 for the fourth year in a row, despite an overall drop in the number of refugees making the journey.

The International Organization for Migration has called the Mediterranean "by far the world's deadliest border," as more than 33,000 migrants have died at sea trying to enter Europe since 2000.

Updated at 1:07 p.m. ET

President Trump insisted Saturday that he is "a very stable genius," following the recent publication of a book that raises questions about his mental state and fitness for office.

Speaking to reporters at Camp David on Saturday, Trump called Michael Wolff, author of Fire and Fury: Inside The Trump White House, "a fraud" and reiterated his earlier claim on Twitter that Wolff is not trustworthy.

The Douglas County Sheriff's office south of Denver says a suspect fired more than 100 rounds in a shooting that killed one police officer and wounded four others, along with two civilians, on Sunday morning.

The officers were shot after responding to an initial report of domestic violence at the Copper Canyon Apartments just after 5 a.m., Sheriff Tony Spurlock said in a news conference.

Over 26 hours and across 39 time zones, the world is celebrating the end of 2017.

New Year's celebrations kicked off in Samoa, Christmas Island and New Zealand as those countries were the first where the clock struck midnight. Here in the U.S., many events are set to occur under heightened security, including in Las Vegas, which is still reeling from the deadliest mass shooting in the nation's modern history three months ago.

Author Peter Zheutlin never wanted a dog, let alone a rescue. He had always believed, as a lot of people do, that rescue dogs are damaged goods.

Now Zheutlin can't imagine life without a dog, and he's become so driven by the issue of stray dogs that he's written two books about it. He tells Here & Now's Lisa Mullins the number of stray dogs has "cascaded out of control" in some parts of the U.S.

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