Fox News cameraperson Pierre Zakrzewski and Ukrainian journalist Oleksandra "Sasha" Kuvshynova were killed in Ukraine after the vehicle in which they were traveling was struck by incoming fire, the US network said on Tuesday.

Zakrzewski, 55, was reporting with another Fox News journalist, Benjamin Hall, on Monday when they came under attack near the capital Kyiv, Fox News CEO Suzanne Scott said in a note to staff. Hall remains in hospital.

Zakrzewski was a veteran war-zone photographer who had covered multiple conflicts for Fox News, including in Iraq, Afghanistan and Syria. Based in London, he had been working in Ukraine since February.

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In a second statement, Scott said Kuvshynova, 24, had been helping Fox's crews navigate Kyiv and the surrounding area while gathering information and speaking with sources.

At least four journalists have died in nearly three weeks of fighting. American filmmaker and journalist Brent Renaud was shot dead by Russian forces in the town of Irpin in Ukraine's Kyiv region, a regional police chief said on Sunday.

On March 1, Ukrainian camera operator Yevhenii Sakun was killed when Russian forces shelled a television tower in Kyiv, according to a social media account by a former colleague cited by the Committee to Protect Journalists.