Syria received its worst ever ranking in the Reporters Without Borders annual press freedom index for 2011Credit: Google Maps
News of the deaths was first reported by Al Jazeera, which said it heard of the attack from activists who were with the journalists in the building.
Al Jazeera also reported that a third journalist was "reportedly injured".
Reuters has named the two journalists as Sunday Times foreign correspondent Marie Colvin and French photographer Remi Ochlik, but this is yet to be confirmed by official sources.
The BBC, which carried an interview with Colvin on Tuesday, states that the Sunday Times journalist was "the only British newspaper journalist in Homs".
Sunday Times publisher News International had not responded to a request for comment at the time of writing.
Syria received its "worst ever" ranking in the Reporters Without Borders annual press freedom index for 2011.
The latest reported deaths follow that of New York Times foreign correspondent Anthony Shadid last week, who died after suffering an apparent asthma attack while reporting from Syria.
Update: Associated Press has reported that France's foreign minister "confirmed the death of a French journalist" in Syria but has not identified the individual.
It was later reported that French officials had identified the journalists as Colvin and Ochlik.
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