BEIRUT (AP) — Syrian government forces marching from different directions in southern parts of the opposition-controlled province of Idlib met around sunset Wednesday, laying siege to several rebel-held towns and villages as well as a Turkish army post, a Syrian opposition war monitor and pro-government activists said.

The rapid advance by the Syrian army in the northwestern province marks a major blow for insurgents in their last remaining stronghold in Idlib, which has been subjected to a government offensive for the past three months.

The new gains by the government came amid intense aerial and ground bombardments during which troops advanced in southern parts of Idlib, which is home to some 3 million people, many of them displaced by fighting in other parts of the country.

The violence came a day after the main insurgent group in Idlib pulled out of Khan Sheikhoun, a key rebel town, as government forces advanced in the area slowly, clearing land mines and explosives. Activists said Syrian troops were in full control of the town Wednesday afternoon.

The withdrawal of al-Qaida-linked Hayat Tahrir al-Sham from Khan Sheikhoun was a blow to the opposition. Syrian government forces have been on the offensive in Idlib and northern parts of Hama province since April 30, forcing nearly half a million people to flee to safer areas further north. The fighting also killed more than 2,000 people, including hundreds of civilians.

Since the early hours of Wednesday, government forces captured Teraei Hill east of Khan Sheikhoun and kept moving west until they met with Syrian troops marching from the other side, according to the Syrian Observatory for Human Rights, a war monitor, and a pro-government activist collective.

The move meant that rebel-held towns and villages in the central province of Hama, including the militants' strongholds of Kfar Zeita and the nearby town of Latamneh, were now besieged. A Turkish observation post in the village of Morek was also under siege.

Turkey, a strong backer of the opposition, has 12 observation posts in and around Idlib — part of an agreement reached last year with the Russians, who support President Bashar Assad's government.

The latest round of fighting has displaced tens of thousands of people since August, when the government intensified its campaign around Idlib.

The Syrian Response Coordination Group, a relief group active in northwestern Syria, reported that nearly 200,000 people have fled the violence over the past 10 days alone.

Earlier on Wednesday, airstrikes hit a hospital in a rebel-held village in Idlib knocking it out of service. There was no immediate word on casualties from the airstrike on the Rahma hospital in Tel Mannas, said the Observatory and the Thiqa news agency, an activist collective.

The Observatory said the hospital was struck four times but that it had been evacuated hours earlier. However, the International Union of Medical Care and Relief Organizations, or UOSSM, said one patient was killed.

Earlier this month, U.N. Secretary-General Antonio Guterres authorized an investigation into attacks on health facilities and schools in the rebel-held enclave, following a petition from Security Council members.