A series of devices packed with ball-bearings exploded outside a provincial headquarters of China's ruling Communist Party, police and reports said.

One person was killed and eight injured in the attack in the northern province of Shanxi, according to a police statement.

"There were several explosions caused by small explosive devices near the party provincial commission in Taiyuan," the capital Shanxi, local police said on a verified social media account.

"Public security officials are currently on the scene and working all-out to investigate the incident," it added.

Ball bearings were seen scattered around the scene, China's official Xinhua news agency reported. They are often used by bomb-makers to increase the chances of blasts inflicting injuries.

"The accident is suspected to be caused by self-made bombs," it said.

State broadcaster CCTV reported that some of the explosives detonated in flowerbeds at the entrance to the party provincial commission.

Xinhua quoted two witnesses near the site who said they heard a loud noise, then saw smoke, followed by a minivan exploding.

Images showed several fire engines on a road, which had been blocked to traffic, and a large crowd on one side of the street.

About 20 cars parked 100 metres away from the site had been damaged, CCTV reported, and local firefighters and police were conducting rescue work and an investigation.

'Terrorist attack'

Chinese authorities maintain tight control over public security in the one-party state and place huge importance on maintaining social order.

While protests happen regularly, incidents of targeted violence are normally extremely rare.

But the Shanxi blasts come a little over one week after a car barrelled into Beijing's Tiananmen Square, killing two tourists and injuring dozens, with the three people inside dying after they set the vehicle on fire.

Authorities termed that incident a "terrorist attack" and have said that it was carried out by several people with links to a separatist group known as the East Turkestan Islamic Movement from China's far-western Xinjiang region, home to the mostly Muslim Uighur minority.

The latest incident comes ahead of a highly anticipated meeting of top party leaders in Beijing this weekend, at which broad economic reforms are among the items expected to be on the agenda.