At least five Iranian police have been killed in an ambush in the restive Sistan-Baluchestan province, Iranian media reported on Friday.

The unidentified assailants struck two units on patrol near the town of Iranshahr, the Fars news agency said, citing local police.

“In this terrorist act, five servants of security and peace were martyred,” it quoted police as saying.

Sistan-Baluchestan, which borders Pakistan and Afghanistan, has long been a flashpoint for clashes between security forces and armed groups, including drug traffickers and separatists.

The province, which is home to a large Sunni Muslim Baloch minority, is one of the poorest regions of the Shia-majority country.

Police said the officers had been on routine patrol when they came under fire. Iranian media published an image of a bullet-riddled police pickup with bodies lying on the ground nearby.

An operation was underway to “track down and identify” the assailants, Fars said.

No group immediately claimed responsibility.

Iran regularly reports deadly ambushes in the province targeting police or Revolutionary Guards.

Authorities blame militant groups, including Jaish al-Adl (Army of Justice).

The latest attack comes after authorities said the security forces had killed seven members of another armed group, Ansar al-Furqan, last week as they foiled an attempted attack.

A day earlier, a police officer was killed in an attack later claimed by Jaish al-Adl.