Tributes have poured in after a British war reporter died in a blast in Afghanistan.
Father-of-three Rupert Hamer, 39, was killed while embedded with US Marines.
The Sunday Mirror's defence correspondent is the first British journalist to have died in Afghanistan.
The newspaper's photographer Philip Coburn, 43, was hurt in the explosion, which also killed a US Marine and left five more with serious injuries.
Hamer, who was married to Helen, had three children, aged six, five and 19 months and had worked for the newspaper for 12 years, taking on the defence correspondent role in 2004.
In response to Hamer's death and Coburn's injuries, Mr Brown said: "I was deeply saddened by this tragic news, and my heartfelt thoughts and sympathies are with the families, friends and colleagues of Rupert and Philip.
"Their courage, skill and dedication to reporting from the frontline was incredibly important and ensured that the world could see and read about our heroic troops. Their professionalism and commitment to our forces will not be forgotten."
Tory leader David Cameron said: "My condolences go to Rupert's family - especially his wife Helen and their three young children. I'd also like to wish Philip Coburn who was badly injured alongside Rupert a speedy recovery."
Hamer believed the only place to report a war was from the front line, according to Sunday Mirror editor Tina Weaver, who said: "He was a seasoned, highly-regarded and brave journalist who had reported from both Iraq and Afghanistan on many occasions."
"He was a fine, fearless, and skilled writer who joined the paper 12 years ago," she said. "Affectionately known as Corporal Hamer in the office, he was a gregarious figure, a wonderful friend who was hugely popular with his colleagues. Above all he was devoted to his wife Helen and their three young children. Our thoughts and condolences are with Helen, his father Nick, who he was so close to, and the children he was so proud of."