Ferguson, Mo., police fired tear gas at demonstrators and arrested two reporters as the St. Louis suburb erupted for a fourth night after a police officer fatally shot an unarmed teen Saturday.
City officials had asked for calm, but police set up barricades and were out in force as the sun went down.
As a protest escalated, officers in riot gear moved in to close a McDonald's restaurant where reporters were writing and charging cellphones.
Reporters Wesley Lowery of The Washington Post and Ryan Reilly of The Huffington Post said on Twitter that police told them to stop recording the events, then took them into custody.
Reilly tweeted that police asked him for his ID when he took a photo. He said he and Lowery were arrested for "not packing their bags quick enough."
Lowery tweeted, "Officers slammed me into a fountain soda machine because I was confused about which door they were asking me to walk out of."
Los Angeles Times reporter Matt Pearce tweeted that when he contacted Ferguson police Chief Thomas Jackson and asked about the arrests of the reporters, Jackson responded, "Oh God."
Pearce said he spoke to the chief a second time and Jackson said he asked the riot command to release the reporters.
The Post is "relieved that Wesley is going to be OK" and "appalled by the conduct of police officers involved," Washington Post editor Martin Baron said. "That behavior was wholly unwarranted and an assault on the freedom of the press to cover the news."
Lowery won the Emerging Journalist of the Year award at the annual convention of the National Association of Black Journalists this month. NABJ President Bob Butler released a statement Wednesday night regarding the arrests.
"Journalists have a constitutionally protected right to work without the government interference," Butler said. "We call on -- and fully expect -- the authorities to investigate what appears to be a violation of the First Amendment and to hold the officers involved to account, if necessary."
Ryan Grin, Washington bureau chief of The Huffington Post, released a statement: "Compared to some others who have come into contact with the police, they came out relatively unscathed, but that in no way excuses the false arrest or the militant aggression toward these journalists. Ryan, who has reported multiple times from Guantanamo Bay, said that the police resembled soldiers more than officers, and treated those inside the McDonald's as 'enemy combatants.' "
Ferguson police could not immediately be reached Tuesday night.