LONDON — A journalist was fatally shot while reporting on a riot in the Northern Irish city of Londonderry on Thursday, authorities said.
Lyra McKee, 29, was described by one colleague as a "rising star."
Dozens of Molotov cocktails were thrown at officers during unrest in the Creggan area of the city, according to the Police Service of Northern Ireland.
Around 100 people, including youths and members of the media, were at the scene when shots were fired before midnight local time.
An eyewitness told the BBC that a gunman fired indiscriminately into a crowd.
Leona O'Neill, a local journalist who was present, wrote on Twitter that she was with McKee when she was hit. She said McKee fell beside a police vehicle Land Rover and officers rushed her to hospital, where she died.
Tributes praising McKee described her as a warm, wonderful person who was passionate about her profession.
McKee had written for publications around the world including The Atlantic and she also edited for California-based news site Mediagazer. Her first book "The Lost Boys" was to be released next year, according to literary agency Janklow & Nesbit UK.
She rose to prominence in 2014 with a blog post describing the struggle of growing up gay in Belfast, the capital of Northern Ireland.
Mark Hamilton, the police force's assistant chief constable, said a murder investigation had been launched.
"We believe this to be a terrorist act. We believe it has been carried out by violent dissident republicans," he added. "Our assessment at this time is that the New IRA are most likely to be the ones behind this."
The New IRA is a small group of republicans who reject the 1998 Good Friday agreement that marked the Irish Republican Army's embrace of a political solution to the long-running violence known as "The Troubles" that claimed more than 3,700 lives.
The riot was the latest in a series of violent incidents in Londonderry this year.
The detonation of a large car bomb outside a courthouse in January highlighted the threat still posed by militant groups opposed to a 1998 peace deal that largely ended three decades of violence in the British-run province. No one was injured in the blast.
House of Representatives Speaker Nancy Pelosi led a congressional delegation to the city earlier Thursday, as part of a trip to show support for the peace agreement politicians in Washington helped to broker.
British Prime Minister Theresa May called McKee's killing "shocking and truly senseless."