Oscar-nominated British photographer Tim Hetherington and his US colleague Chris Hondros have been killed while covering the fighting in the Libyan city of Misurata, the UK's Foreign Office has confirmed.
Mr Hetherington, who had won a World Press Photo of the Year award for his coverage of Afghanistan and had also made prize-winning film documentaries, was said by friends and colleagues to have died from a mortar round while on the front line.
The photographer, who was on assignment for the news agency Panos, is the first known British casualty of the Libyan conflict.
Mr Hetherington wrote on Twitter the day before he died:
"In besieged Libyan city of Misurata. Indiscriminate shelling by Qaddafi forces. No sign of Nato."
An American colleague, Chris Hondros, a photographer for Getty Images, died after being seriously wounded, according to Getty's director of photography, Pancho Bernasconi.
Mr Hondros, 41, had been nominated for a Pulitzer prize in 2004 and also lectured and wrote on war in the United States. Both men lived in New York.
Two other journalists were said to have been injured in the incident.
One of those injured was reported to be Guy Martin, a British photographer with Panos, who was receiving treatment in hospital last night.
The photographers were among a group caught by mortar fire on Tripoli Street, the main thoroughfare leading into the centre of Misurata, according to reports.
Spanish photographer Guillermo Cervera said: “It was quiet and we were trying to get away and then a mortar landed and we heard explosions.”
Tributes have been left on Mr Hetherington's Facebook page, from journalists, soldiers and admirers of his work. One Platoon Sergeant wrote: "From one Soldier who looks through a scope, to another one who used a lens, THANK YOU! R.I.P Brother."
Mr Hetherington, 40, who was from Liverpool but had dual British and American nationality, read English literature at Oxford University before becoming a photographer and film-maker.
He spent eight years in West Africa, covering the Liberian and Sierra Leone civil wars there, before working in Afghanistan.
His first film, Restrepo, which covered the lives of a platoon of soldiers in Afghanistan, which was last year nominated for an Oscar.
He spent 15 months embedded with the Second Platoon in one of the most dangerous valleys in Afghanistan with journalist Sebastian Junger; extracts from the experience were published in the Telegraph Magazine last year.
James Golston of ABC-TV News USA, who worked with Mr Hetherinton on Nightline, a documentary about the war in Afghanistan, described him as “one of the bravest photographers and filmmakers I have ever met”.
He said: "During his shooting for the Nightline specials he very seriously broke his leg on a night march out of a very isolated forward operating base that was under attack.
“He had the strength and character to walk for four hours through the night on his shattered ankle without complaint and under fire, enabling that whole team to reach safety.”
Mr Hetherington last year described some of his experiences in Afghanistan as “pretty traumatic events”.
He said: “The thing about the wars in Afghanistan, they've been known as the ghost wars, you know, because not often does one really see the enemy.”
His last film, which he posted on the video-sharing website Vimeo, was an attempt to "locate myself after ten years of reporting". He described it as "a kaleidoscope of images that link our western reality to the seemingly distant worlds we see in the media".
A Foreign Office spokesman said: "We are offering consular assistance to the family.”