Some three attackers were killed while one security personnel was injured after militants attacked an intelligence office in southern Afghanistan' s Kandahar city on Sunday morning, an official source said.

The attack took place after one militant rammed a car bomb to the wall of the building which houses the fast-reaction forces of the National Directorate of Security (NDS), the country's intelligence agency, the source told Xinhua anonymously. "Shortly after the initial blast which occurred at around 6:00 a.m. (local time), two other militants ridding motorbikes approached the building and clashed with the NDS forces. They were shot dead before entering the compound," he said. "One NDS security officer was wounded as we know. But details will be revealed after an ongoing investigation," the source added.

The attacked building is located close to an industrial area. Several factories at the site were damaged besides the targeted building in the city which is the provincial capital of southern Kandahar province.

Security forces have cordoned off the area for precautionary measures.

Kandahar, the birthplace of the Taliban, is notorious for poppy growing.

No group has claimed responsibility yet for the attack, but the Taliban insurgent group routinely claims responsibility for such attacks.

The Taliban-led insurgency has been rampant since mid-April when the militant group launched a yearly rebel offensive against Afghan security forces.