London — A young journalist was killed in Northern Ireland overnight in what police are treating as a "terrorist" incident. Lyra McKee, 29, was shot during riots ahead of the anniversary of the revolt that led to Irish independence from Britain.

McKee was an investigative reporter and editor. Her work often focused on the conflict in Northern Ireland, known as "The Troubles," which saw decades of violence between those who wanted Northern Ireland to remain part of the United Kingdom, known as "unionists," and those who wanted it leave and join a united Republic of Ireland, known as "republicans." The conflict officially ended with a peace accord, the Good Friday Agreement, in 1998.

The latest rioting broke out in Londonderry after the Northern Irish police, fearing violence over the weekend, conducted a series of raids searching for weapons and ammunition. Gunshots were fired towards police and McKee was struck, they said.

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"At this stage we believe her murder was carried out by a violent dissident republican," Assistant Chief Constable for District Policing Mark Hamilton said in a statement. "This murder demonstrates all too starkly that when terrorists bring violence and guns into the community, members of the public are placed in severe danger. It is abundantly clear that they do not care who they harm."

"The New IRA are most likely to be the ones behind this and that forms our primary line of inquiry," Hamilton said, referring to a small dissident republican group.

McKee was seen as a rising star, named to Forbes "30 under 30" list of notable media figures in 2016. She had written for BuzzFeed and the Atlantic, and recently signed a deal to write two books.

Journalist Lyra McKee smiles outside the Sunflower Pub on Union Street during a portrait session in Belfast, Northern Ireland May 19, 2017. Jess Lowe Photography

Her death comes as police in Northern Ireland are worried about a rise in dissident violence, BBC News reports. Before her death, McKee tweeted a photo of the riots with smoke rising in the distance and the text, "Derry tonight. Absolute madness."

Police said they were concerned about a possible spate of attacks over the weekend. "We believe that dissident republicans have a number of attacks planned and we assess it is likely that these would have been used over the Easter period," Hamilton said.

In response to McKee's death, Irish Prime Minister Leo Varadkar said: "We cannot allow those who want to propagate violence, fear and hate to drag us back to the past."

U.K. Prime Minister Theresa May called McKee's death "shocking and truly senseless," and opposition leader Jeremy Corbyn said it was "a reminder of the vital importance of protecting the Good Friday Agreement and Northern Ireland peace process."

The Northern Ireland secretary in the U.K government, Karen Bradley, said: "Those responsible for last night's violence have nothing to offer anyone in Northern Ireland. Their intolerable actions are rejected by the overwhelming majority of people who want to build a peaceful and more prosperous future for everyone in Northern Ireland," according to the Financial Times.

"These people should disband," said Michelle O'Neill, deputy leader of Irish republican party Sinn Fein. "These people should desist, and they have no role to play in our community."

U.S. Speaker of the House Nancy Pelosi, who is visiting the region, joined in a minute of silence for McKee, calling the fact that it came on Good Friday "especially poignant."