Tehran, Dec 6 (IANS): At least two people were killed and 28 injured in a suicide bombing at a police headquarters in Iran's southeastern port city of Chabahar on Thursday, officials said.

Three of the 28 people injured in the attack were in grave condition, Mohammad Naseh, a chief medic at an emergency centre in the city was quoted as saying by state-run IRNA news agency.

Following the attack, gunfire was heard in Chabahar -- located in the province of Sistan and Baluchestan, near the border with Pakistan -- where militant Sunni groups opposed to the ruling Shia government, smugglers and drug traffickers operate.

Chabahar Governor Rahmdel Bamri said that the suicide bomber was killed after he blew himself up in the attack. An investigation was initiated into the explosion, for which no group has claimed responsibility as of yet, IRNA reported.

According to the Iranian media, immediately after the bomber detonated the car bomb, gunmen attempted to storm the police headquarters but were killed by security forces.

Terror attacks are frequent near Iran's borders with Pakistan (east) and Iraq (west).

In September, 29 people were killed during an attack on a military parade in Iranian city of Ahvaz in September.

In June 2017, a double attack on the Iranian Parliament and the mausoleum in Tehran of former supreme leader Grand Ayatollah Ruhollah Khomeini, left 17 dead and over 50 injured.

Both attacks were claimed by the Islamic State terror organization.