TEHRAN, Iran – A pair of gunmen opened fire on a police patrol in Iran's Kurdish region on Thursday, killing four officers and a bystander, the Iranian official news agency reported.

The attack took place in Sanandaj, the capital of Iran's Kurdistan province some 310 miles (500 kilometers) west of Tehran, where authorities have been battling a separatist Kurdish movement for years.

"In this terrorist incident five were killed including four policemen and a pedestrian," Col. Ebrahim Kazeminejad, the provincial deputy police chief told the IRNA news agency.

The two gunmen were members of "counterrevolutionary groups" he said and added that they were using Kalashnikov rifles.

Five other policemen and four civilians were wounded in the attack, one of them in serious condition.

Efforts were under way to apprehend the gunmen, he said.

No group immediately claimed responsibility for the attack.

In September, a deadly bombing killed 12 and injured scores of civilians at a military parade in the Kurdish city of Mahabad. Iranian forces later crossed into neighboring Iraq and killed 30 Kurdish fighters in retaliation.

Iran has long fought Kurdish separatist groups who say they are struggling for more rights for the minority, which makes up 7 percent of Iran's 75 million people.