BEIRUT — Syrian government forces have launched a counter-attack to recapture a gas field seized by Islamic extremists, activists said Saturday, as the death toll from three days of fighting rose to more than 200 people killed.

The intense fighting in the Shaer field, which lies in the desert region of Palmyra in the central province of Homs, has been among the deadliest battles between government forces and the Islamic State group since the start of the Syrian uprising more than three years ago.

Fighters from the Islamic State group have in the past few weeks seized a huge chunk of territory straddling the Iraq-Syria border, where they declared a self-styled caliphate. They also have captured much of Syria’s oil-rich eastern province of Deir el-Zour.

The Britain-based Syrian Observatory for Human Rights said Syrian special forces launched an attack late Friday on the Shaer field and regained parts of it.

A Homs-based activist who goes by the name of Beibares Tellawi confirmed that troops attacked fighters from the Islamic State group.

“The fighting today is mostly hit-and-run attacks,” Tellawi said via Skype. “Large numbers of (President Bashar) Assad’s forces are attacking the field.”

The Observatory said that the number of troops, guards and workers killed in the gas field since it was captured Thursday has risen to 270, adding that some were captured and killed by militants. Tellawi said the death toll was at least 200.

The Observatory said Friday’s clashes alone left 51 soldiers either dead or wounded. It said 40 Islamic State fighters have been killed so far, while Tellawi said the number is more than 30.

The fate of 90 other gas field workers and guards is still unknown, said the Observatory, which relies on a network of activists inside Syria.

In the rebel-held Damascus suburb of Douma, a car bomb exploded Saturday, killing at least nine people and wounded others, the Observatory said. The area has been struck by several car bombs in the past month that killed and wounded dozens.

The Observatory and Ahmad al-Masalmeh, an opposition activist in the southern province of Daraa, also reported intense shelling and air raids by government forces in the region that borders Jordan.

Syria’s state news agency SANA said the army “hit terrorist dens,” killing and wounding scores of militants in several villages and towns in Daraa, including the villages of Tafas, Inkhil, Atman and Dael.

An unnamed Jordanian military official quoted by Jordan’s state news agency said that border guards have received 411 Syrian refugees over the past three days. The official said 46 of them were seriously wounded and were admitted to field hospitals and that 12 died.

The Syrian uprising began in Daraa in March 2011 with anti-government protests. The revolt later turned into a civil war that has killed at least 170,000 people and displaced some 9 million, a third of the country’s pre-war population.

Also Saturday, the United Nations children’s agency said it was able to reach the Damascus suburb of Moadamiyeh for the first time since 2012. Moadamiyeh has been under a government siege that activists say killed a number of people dead because of lack of food and medicine.

A statement by UNICEF said the agency provided supplies directly to children and their families.

On Monday, some 13 Syrian Arab Red Crescent trucks loaded with 1,000 food parcels crossed into Moadamiyeh.

UNICEF estimates there are 9,200 children in the suburb who are in desperate need of aid.

Copyright 2014 The Associated Press.