Four riot police officers have been killed near Grozny, the capital of the Russian North Caucasus republic of Chechnya, as their car was attacked, a police spokesman told RIA Novosti.

“Unknown assailants opened fire from automatic weapons at a police car near the locality of Alkhan-Kala,” the spokesman said, adding that the incident occurred late on Friday. “Four policemen inside the car died of wounds.”

Police are conducting manhunt activities. An investigation is underway.

Local authorities have waged an ongoing campaign in recent years against an Islamist insurgency that often targets local law enforcement and security officials in ambushes and suicide bombings.

Since the official end of the federal anti-terrorism operation in Chechnya in April 2009, the insurgency has spread through other North Caucasus republics.