A suspected suicide bombing outside police headquarters in Indonesia's city of Medan in North Sumatra killed the perpetrator and wounded some officers on Wednesday, police said, just a month after an attack on a former security minister.

The motive for Wednesday's attack was not immediately clear, but Indonesia, the world’s most populous Muslim-majority country, has suffered a resurgence in homegrown militancy in recent years, with some attacks targeting police.

The suspected suicide bomber had died in the attack, a spokesman for the North Sumatra police, Tatan Dirsan Atmaja, said by telephone, adding that some police officers were wounded in the blast at 8:40 am (0140 GMT).

Television broadcast images of people rushing out of buildings around the headquarters.

National police spokesman Dedi Prasetyo said the blast happened in a car park near an area where people were queuing for clearance letters from police.

"We're on alert right now," Prasetyo told Kompas TV. "The explosion didn't reach the centre for the clearance letter service, it was just in a parking lot."

In recent years, Islamic radicals, some tied to the Islamic State-inspired militant group Jamaah Ansharut Daulah (JAD), have targeted police in a series of attacks.

The latest attack comes a month after a suspected Islamist stabbed and wounded Wiranto, Indonesia's former security minister, who uses one name.