BEIRUT (AP) — Heavy fighting broke out between rebels and President Bashar Assad’s forces in parts of Damascus on Wednesday, as twin car bombs detonated in the central province of Homs, killing at least 12 people, activists said.

The clashes in Damascus were the worst violence to hit the capital in weeks. Fighting was focused in the city’s western districts, and residents in the heart of Damascus said the heavy thud of shelling was louder than in recent months when government forces tried to dislodge rebels from the capital’s suburbs.

Damascus has not seen the same degree of fighting as Syria’s other urban centers like Aleppo and Homs, where whole neighborhoods have been destroyed. While the government has lost control of parts of those cities, it has kept a tight grip on the capital despite the rebels’ attempts to storm the city center from enclaves on its outskirts.

Rami Abdul-Rahman, director of the Britain-based Syrian Observatory for Human Rights, said Wednesday’s shelling of Jobar and Qaboun is part of a wider government offensive against towns and villages near the capital that have been opposition strongholds since the beginning of the anti-Assad uprising in March 2011.

A government official said army troops are chasing rebels in the suburbs of Harasta, Sbeineh, and Jober. The official spoke on condition of anonymity because he was not authorized to brief the media.

Fighting also erupted in the central province of Homs, where blasts targeting a military complex killed at least 12 people and injured dozens of others, activists said.

There were conflicting reports about the nature of the explosion in the city of Palmyra. The Observatory said two car bombs blew up near a compound that houses a military intelligence branch and a state security agency there, killing 12 members of Syrian security forces and injuring 20 people, including eight civilians.

State-run SANA news agency confirmed the attack, but said two suicide bombers detonated cars packed with explosives near a garage in a residential area of the city, killing an unknown number of people, wounding dozens and causing significant material damage in the area.

After the blasts, rebels clashed with government soldiers guarding the compound, according to the Observatory, which relies on reports from activists on the ground.

There was no immediate claim of responsibility, although car bombs and suicide attacks targeting state institutions have been a hallmark of Islamic militants fighting alongside Syrian rebels aiming to topple Assad, whose family has ruled Syria for more than 40 years.

Homs has been an opposition stronghold since the Syrian uprising erupted nearly two years ago. The province and its capital of the same name were the scene of massive protests early in the revolt, which has since devolved into a civil war that has turned urban centers like Homs and the northern city of Aleppo into battlefields.

The United Nations say more than 60,000 people have been killed since the conflict started. At least 700,000 Syrians have fled abroad, seeking shelter in neighboring countries like Jordan, Lebanon and Turkey, while more than one million people have been displaced within Syria during 22 months of fighting, according to aid agencies.

Copyright 2013 The Associated Press.