In a statement, editor John Witherow said that Colvin, who secured a number of journalism awards during her career, including foreign reporter of the year at the British Press Awards, was "much more than a war reporter".
"She was a woman with a tremendous joie de vivre, full of humour and mischief and surrounded by a large circle of friends, all of whom feared the consequences of her bravery."
Witherow added that freelance photographer Paul Conroy was injured in the attack in Homs, but that the "extent of his wounds" are not yet known although "the early reports suggest he is not too seriously hurt".
"We are doing what we can to get him to safety and to recover Marie's body," Witherow said.
Colvin was interviewed by a number of British broadcasters on Tuesday, including the BBC and Channel 4 News, when she told of "ferocious shelling". Channel 4 News reports this interview was carried out "hours before she was killed".
The BBC said that the Sunday Times journalist was "the only British newspaper journalist in Homs".
In his statement, Witherow added that Colvin "was an extraordinary figure in the life of the Sunday Times, driven by a passion to cover wars in the belief that what she did mattered".
"She believed profoundly that reporting could curtail the excesses of brutal regimes and make the international community take notice. Above all, as we saw in her powerful report last weekend, her thoughts were with the victims of violence.
"Throughout her long career she took risks to fulfill this goal, including being badly injured in Sri Lanka. Nothing seemed to deter her. But she was much more than a war reporter. She was a woman with a tremendous joie de vivre, full of humour and mischief and surrounded by a large circle of friends, all of whom feared the consequences of her bravery.
"Marie was recruited to the Sunday Times more than a quarter of a century ago by David Blundy, her predecessor as Middle East correspondent, who was himself killed in El Salvador in 1989. It shows the risks that foreign correspondents are prepared to take in the pursuit of the truth.
"Marie will be missed sorely by all of us and her many friends."
It has also reportedly been confirmed by French authorities that photographer Remi Ochlik, one of the World Press Photo winners for 2012, was also killed in the attack.
News Corporation chairman Rupert Murdoch also issued a statement in response to the news, in which he describes Colvin as "one of the most outstanding foreign correspondents of her generation".
He added that the building Colvin was in "had been turned into an impromptu press centre by the rebels".
"Marie had fearlessly covered wars across the Middle East and south Asia for 25 years for The Sunday Times. She put her life in danger on many occasions because she was driven by a determination that the misdeeds of tyrants and the suffering of the victims did not go unreported.
"This was at great personal cost, including the loss of the sight in one eye while covering the civil war in Sri Lanka. This injury did not stop her from returning to even more dangerous assignments.
"Our immediate thoughts are with her family."
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