Reuters reports: Opposition fighters battled Syrian government forces in Damascus into the early hours of Monday in what residents described as the fiercest fighting yet inside the capital.

Activists said the fighting spread from the south of the city to a second area as night fell. At least five people were killed and dozens wounded, locals said.

The spread of fighting came as U.N. peace mediator Kofi Annan was due to fly to Moscow for a two-day visit in which he will meet Russian President Vladimir Putin who has resisted Western calls to increase pressure on Syrian leader Bashar al-Assad.

Numerous Damascus residents contacted by Reuters said they could hear loud explosions, persistent gunfire and sirens wailing overnight, and described the fighting as the worst so far of the 17-month uprising against Assad.

Thick black smoke was visible above the Damascus skyline in live Internet video links. Government troops closed the airport road, activists said.

“I can’t believe it, it sounds incredibly close. I hear shooting and other stuff, like blasts. I can hear the sounds of ambulances rushing past. I am so afraid. People may die tonight,” said a resident contacted by telephone in a district close to the fighting.

Activist Samir al-Shami, who spoke to Reuters by Skype from Damascus, said the fighting was under way in the al-Tadamon district in the capital’s south, after sustained battles began at nightfall on Saturday in the nearby Hajar al-Aswad district.

“There is the sound of heavy gunfire. And there is smoke rising from the area. There are already some wounded and residents are trying to flee the area,” he said, using Skype to show live video images of smoke visible over the skyline.

“There are also armored vehicles heading towards the southern part of the neighborhood,” he said.

Another activist reached by Skype said the fighting later spread to al-Lawan, a neighborhood on the southwestern outskirts of the capital.

A third activist, who also asked not to be identified, said: “We’ve been expecting things to worsen in Damascus after the army crushed the rebellions in some of the suburbs, like Douma outside the capital. There were thousands of fighters in some of those suburbs. Some of them were killed but a lot of them fled and they’ve been heading to the capital itself.”