Eyewitnesses said Mr Dana, a Palestinian, was shot by soldiers on an American tank as he filmed outside Abu Ghraib prison, in western Baghdad.
His last pictures show a US tank driving towards the photographer outside the prison walls. Several shots ring out from the tank, and Mazen Dana’s camera falls to the ground.
The US military in Iraq said an investigation was under way and had no immediate information on whether American forces fired the shots that killed Mr Dana.
“Coalition forces engaged an individual in the vicinity of the Abu Ghraib prison,” Pentagon spokesman Bryan Whitman said in Washington.
“The individual was later identified as a reporter. The individual was evacuated to the 28th combat support hospital and pronounced dead on arrival,” he said.
“The incident is under investigation.”
Mr Dana’s death brings to 17 the number of journalists or their assistants who have died in Iraq since the invasion began on March 20. Two others have been missing.
Mazen Dana is the second Reuters cameraman to be killed since the US-led forces invaded Iraq to topple President Saddam Hussein.
On April 8, Taras Protsyuk, a Ukrainian based in Warsaw, died when a US tank fired a shell at the 15th floor of the Palestine Hotel, the base for foreign media in Baghdad.—Reuters