BEIRUT (AP) -- The Latest on developments in Syria (all times local):
The Islamic State militants came into the Syrian town of Qaryatayn with a hit list. By the time they left three weeks later, more than 70 civilians had been killed - shot or beheaded, their bodies dumped in farms and ditches.
The apparent revenge killings in the central Syrian town underscore the ability of the extremist group to inflict heavy losses even when it is in retreat.
News of the gruesome slayings began to emerge late Sunday, after IS militants were driven out by advancing government troops.
One former resident says his surviving family members walked for miles to find cell phone coverage so they could tell him of the deaths of his uncle, two cousins and a fourth relative. Another uncle remains missing.
Abdullah AbdulKarim says the militants "came into town with a hit list," and that 35 of the 50 militants who overran the town late last month were originally from Qaryatayn. He said the militants accused many of their victims of collaborating with the government but many others were also caught in the revenge killing.
Syrian officials and activists say the bodies of at least 67 civilians, many summarily killed by the Islamic State group, have been discovered in a central town in Syria that government forces retook from the extremists over the weekend.
A senior Syrian official described the attack as a "shocking massacre," saying the search for and documentation of those killed in the town of Qaryatayn is still underway.
Activists say some were shot in the street as IS militants retreated from the town because they were suspected of working with the government. At least 35 had been shot dead, their bodies dumped in a shaft.
The militants have been retreating across northern and eastern Syria, days after having been defeated in Raqqa, the one-time "capital" of the group's self-proclaimed caliphate. The killings raise the specter of more revenge attacks by the group while it fights to hang on to its last strongholds in Syria.
Pro-government media is reporting that Syrian troops have taken up a position allowing them to fire down on a supply route between an Islamic State-held town on the Iraqi border and a nearby desert outpost.
Pro-government forces are closing in on the frontier town of Boukamal, the last major IS stronghold in the country after the militants were driven from their de facto capital in the northern city of Raqqa as well as the eastern town of Mayadeen.
The Central Military Media, a pro-military media outlet, said Monday Syrian troops and allied militias have encircled the T-2 pumping station in southern Deir el-Zour province following clashes with the militants.
A race is underway between U.S.-backed Syrian forces and Russia-backed government troops in the oil-rich Deir el-Zour province. In a swift advance Sunday, U.S.-allied Syrian forces captured the country's largest oil field from IS.
The spokesman for the U.S.-led coalition fighting Islamic State militants says contacts with Russia are underway to avoid friction on the ground between U.S.-allied fighters and Syrian troops backed by Moscow around Syria's largest oil field, coveted by both sides.
Col. Ryan Dillon told The Associated Press on Monday that the coalition will continue to "de-conflict" with the Russians, to ensure allied forces and the coalition air support can operate safely in and around the Al-Omar oil field.
The U.S.-backed Syrian Democratic Forces captured Al-Omar on Sunday, narrowly beating the Russia-backed Syrian troops who were also advancing toward it.
Dillon says SDF fighters are fighting remaining IS militants in a housing complex adjacent to the oil field. He says the SDF will continue to secure key areas and will attack further into IS-held areas along the border with Iraq and in the oil-rich region of Deir el-Zour.
A senior Syrian official says the killing of more than 60 civilians in a town taken back by government troops from Islamic State militants is a "shocking massacre."
Talal Barazi, the governor of Homs province where the discovery was made, says the search and documentation of those killed in the town of Qaryatayn is still under way.
Barazi told The Associated Press on Monday that most of the bodies were of townspeople who were government employees or were affiliated with Syria's ruling Baath party.
Barazi says at least 13 residents remain missing while six bodies have not been identified.
He says the killings went on for the three weeks that IS was in town and "terrorized" its residents.
Government forces regained control of Qaryatayn on Saturday.
Syrian activists are reporting that at least 65 bodies of civilians have been found in a central town retaken by government forces from the Islamic State group. Most of the victims are believed to have been killed by IS.
The Britain-based Syrian Observatory for Human Rights says the number of those killed in Qaryatayn, in central Homs province, is likely to rise.
The Observatory says most of the dead were killed during the militant group's three-week seizure of the town. Syrian troops and allied fighters regained control of the town on Saturday.
The activist-run Palmyra Coordination Committee has published the names of the killed. It says at least 35 of the victims were found shot and their bodies dumped in a shaft.
IS has suffered major setbacks in recent months.