All but a few dozen residents have fled the ancient Syrian city of Palmyra following a barrage of Syrian government air strikes on the city, an activist in the area has told Al Jazeera.
The air strikes since Friday have killed more than 100 people, including an estimated 33 civilians and 70 fighters believed to belong to the Islamic State of Iraq and the Levant (ISIL) group, the UK-based Syrian Observatory for Human Rights said on Wednesday.
Raids by warplanes and helicopters using barrel bombs and missiles left at least 12 civilians and 20 fighters dead on Tuesday alone.
ISIL took over Palmyra in May, making it the target of regular goverment attacks in recent months.
"We're going into the third day of indiscriminate air strikes, missiles and barrel bombs," Khaled al-Homsi, a member of the Palmyra Coordination activist group, told Al Jazeera on Wednesday night.
Read more: Palmyra caught between two histories
Most civilians have fled the city to neighbouring towns located on its eastern outskirts, according to Homsi.
"There are only a few dozen civilians still in the main part of the city," he said, adding that some people have taken refuge in improvised bomb shelters.
"There are still a lot of ISIL fighters in the city, but they are now in retreat, in self-defence mode because of the airstrikes," Homsi said.
The attacks on Palmyra follow a delivery of Russian weapons, including warplanes, to the Syrian government.
"Russian weapons are starting to have an effect in Syria," the military official told AFP on Tuesday. The US has expressed concern over Russia's military build-up in Syria.
Read more: If Palmyra is destroyed
The Syrian military for the first time used Russian drones against rebels on Wednesday, a security official told the AFP news agency.
Palmyra was a popular destination for tourists who came to see its once well-preserved archaeological attractions, recognised by UNESCO as a World Heritage Site.
Last month ISIL behead Khaled Asaad, an 82-year-old Syrian archaeologist who worked for 50 years as the head of antiquities in the city.
Since ISIL took control of the city, its fighters have also destroyed several historic sites. Fighters blew up the 2,000-year old temple of Baal Shamin structure on August 23. A week later they used 30 tonnes of explosives to partially destroy the nearby Temple of Bel.
In July ISIL released a video of 25 government soldiers being killed by teenagers in Palmyra's ancient amphitheatre. The Syrian Observatory first reported the executions on May 27, less than a week after the group captured the city.
The observatory estimated earlier this year that ISIL controls more than half of Syria's territory.
The Syrian conflict, which began as a peaceful protest in 2011, has led to at least 250,000 deaths, according to the United Nations. More than half of Syria's prewar population of 22.4 million has been internally displaced or fled abroad.
Source: Al Jazeera and agencies