Unknown attackers launched a gun and grenade attack on a court building in southeast Iran Saturday, killing six people — including a child — and wounding 20, state TV reported.

The report said security forces killed three of the gunmen in the armed clash in the country’s restive southern province of Sistan and Baluchestan. It did not identify any of the victims.

State TV said the attack happened in the province’s capital city of Zahedan. Police and security forces immediately took control of the site, 1,130 kilometers or 700 miles southeast of the capital, Tehran.

A report by the semiofficial Tasnim news agency, believed to be close to security forces, blamed the attack on the militant group Jaish al-Adl, which wants independence for Iran’s eastern Sistan and Pakistan’s southwestern Baluchistan provinces.

The province, bordering Afghanistan and Pakistan, has been the site of occasional deadly clashes involving militant groups, armed drug smugglers and Iranian security forces.

In October, an attack on an Iranian police convoy in the province killed at least 10 officers.

Sistan and Baluchistan province 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.