DAMASCUS - Four members of Syria's Internal Security Forces were killed, and a fifth was wounded Sunday evening when gunmen opened fire on their patrol in the city of Maarat al-Numan in Syria's northwestern Idlib province, according to official media and a war monitor.

The state-run SANA news agency said in a brief report that the shooting targeted Internal Security Forces in Maarat al-Numan, leaving four dead and one wounded, without providing further details.

In a separate statement posted on its Telegram channel, Syria's interior authorities said the victims were members of the Road Security Administration who were carrying out their duties on a road in southern Idlib. The authorities said specialized security units had launched intensive operations in the area to track down those involved in the attack.

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The Britain-based Syrian Observatory for Human Rights, a war monitor, reported that the patrol was ambushed near the southern bridge area of Maarat al-Numan, resulting in four deaths and additional injuries.

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The shooting comes amid heightened security concerns in Syria following a deadly incident a day earlier near the city of Palmyra in Homs province, where a gunman opened fire during a joint Syrian-US patrol, killing at least three Americans -- two soldiers and one interpreter -- and prompting expanded security operations against suspected Islamic State cells in central Syria.