Anja Niedringhaus and Kathy Gannon
Anja Niedringhaus (left) was killed and Kathy Gannon was injured when a man dressed as a policeman opened fireGetty / Twitter

Associated Press Anja Niedringhaus, who was killed in the eastern Afghanistan province of Khost by an Afghan policeman, was an internationally renowned war photographer who had been covering conflicts from Bosnia to Afghanistan for more than 20 years.

Born in the German town of Hoxter, North-Rhine Westphalia, Niedringhaus earned a Pulitzer Prize in 2005 as part of a team of AP photographers covering the Iraq War.

She started working as a freelance photographer at just 17, when still in high school.

She then moved on to study German literature, philosophy and journalism in Göttingen. Niedringhaus joined the European Press photo Agency (EPA) as a staff photographer in Frankfurt in 1990.

As chief photographer for the EPA, she covered the conflict in the former Yugoslavia.

In 2002, she joined the Associated Press as a staff photographer in Geneva, Switzerland.

From 2002, she went on covering wars and political events in Iraq, the Gaza Strip, Israel, Kuwait and Turkey. She has received numerous awards for her work, including the Pulitzer Prize in the breaking news category, with a team of AP photographers for their coverage of the war in Iraq, and the Courage in Journalism Award from the International Women's Media Foundation, both in 2005.

According to The Atlantic, Niedringhaus has done a "remarkable job" covering the complex and dangerous Afghanistan war "telling people's stories with a strong, consistent voice, an amazing eye for light and composition, and a level of compassion that clearly shows through her images".

Here are some Twitter reaction to the tragic news: