Police in China have captured a man suspected of starting a fire on a public bus that killed 17 people and injured 32 on Tuesday, state media said.

Authorities cornered Ma Yongping at a construction site after flames engulfed the vehicle in Yinchuan, the capital of the remote Ningxia region, according to a post on a verified social media account of state broadcaster CCTV.

Images posted online showed the bus engulfed in flames and a short video of police in yellow rain jackets gathering around the smoking and charred remains.

The city's mayor told a press conference the local public security bureau was collecting DNA samples to identify the dead, according to an official social media account for the city.

CCTV posted a list of the names of 32 injured ranging in age from 20 to 65, adding that eight had suffered serious injuries.

Authorities did not give any indication of a motive.

There have been several cases of attacks on Chinese public transport, especially buses, in recent years. In 2013 a suicidal man started a fire on a vehicle in Xiamen in the eastern province of Fujian that killed 47 people including himself.

Unverified pictures on social media Tuesday showed what appeared to be the Yinchuan suspect perched on top of a half-finished building, as though preparing to jump.

Police negotiated with him for four hours before arresting him, CCTV said in a post that included a picture of a man in handcuffs being led away.

The broadcaster had previously posted pictures of the 33-year-old along with personal information, including the fact that was a graduate of a technical college. It said police were "investigating and pursuing" him for his role in "a serious crime".