Gunmen ambushed a Syrian police patrol in a coastal town Thursday, leaving at least 13 security members dead and many others wounded, a monitoring group and a local official said.

The attack came as tensions in Syria's coastal region between former President Bashar al-Assad's minority Alawite sect and members of Islamic groups escalate. Assad was overthrown in early December in an offensive of insurgent groups led by the Islamist Hayat Tahrir al-Sham.

The U.K.-based Syrian Observatory for Human Rights said the ambush in Jableh, near Latakia, killed at least 16. It added that security forces killed 28 gunmen loyal to Assad as well as three civilians.

Rami Abdurrahman, head of the monitoring group, said the gunmen who ambushed the police force were Alawites. He added that on Thursday night, pro-Assad gunmen were in full control of the former president's hometown of Qardaha.

"These are the worst clashes since the fall of the regime," Abdurrahman said.

A local official in Damascus told The Associated Press that 13 members of the General Security directorate were killed in the ambush. The official spoke on condition of anonymity because he was not authorized to release security information to the media.

Conflicting casualty figures are not uncommon in the immediate aftermath of attacks in Syria's 13-year conflict, in which a half-million people have been killed. The observatory gave the death toll on both sides, while the official gave only the numbers of police officers killed.

The pan Arab Al Jazeera TV broadcaster said its cameraman, Riad al-Hussein, was wounded while covering the clashes.

State media reported that authorities imposed a 12-hour curfew in the nearby city of Tartus, where people were urged to stay home and avoid gatherings in public places.

The SANA state news agency reported that large reinforcements were being sent to the coastal region to get the situation under control.

The Syrian Observatory said helicopter gunships took part in attacking Alawite gunmen and Jableh and nearby areas. It added that fighters loyal to former Syrian army General Suheil al-Hassan took part in the attacks against security forces.

Tensions have been rising in Syria with reports of attacks by Sunni militants against Alawites, who had ruled in Syria for more than five decades under the Assad family. These incidents have occurred despite the fact that officially the new authorities have said they are against collective punishment or sectarian vengeance.

Sajed al-Deek, a security official, was quoted by local reporters as saying the situation was under control, adding that Alawites had nothing to do with the gunmen who attacked security forces earlier Thursday.