Iran’s state media said security forces were able to release hostages taken by gunmen Thursday following clashes in three separate areas in southeastern Iran that left 18 terrorists and 10 troops dead.

The fighting erupted overnight in Sistan and Baluchistan province when gunmen opened fire on Revolutionary Guard posts in Rask and Sarbaz towns and a coast guard station in Chahbahar city, some 1,400 kilometers (870 miles) southeast of the capital, Tehran, the agency said.

The gunmen took several civilians hostage at two sites and some of the assailants wore suicide vests, state TV reported. Shootouts ensued before security forces gained control of the three areas.

The 10 security forces killed included six members of the Revolutionary Guard and its affiliated troops, two policemen and two members of coast guard, state TV said. At least 10 others were injured, some of them in serious condition, it said.

State media blamed the militant group Jaish al-Adl, which allegedly seeks greater rights for the ethnic Baluch minority. No group claimed responsibility.

Authorities arrested two militants from the group Thursday on suspicion of involvement in the clashes, state TV said.

The restive area, bordering Afghanistan and Pakistan, has been the site of occasional deadly clashes involving the militant group, armed drug smugglers and Iranian security forces. In December, militants killed nearly a dozen police officers in an attack on a police station in the province.

The area is one of the least developed parts of Iran. Relations between the predominantly Sunni Muslim residents of the region and Iran’s Shiite theocracy have long been strained.