Beijing, China (CNN) -- Police in western China detained a man suspected of driving an explosive-laden tricycle into a crowd on Thursday, killing seven people and injuring 13, a government official told CNN.

"The explosion took place around 10:30 a.m. on the outskirts of Aksu city in southern Xinjiang," said Hou Hanmin, deputy director of Xinjiang's information department. "Police have determined it was an intentional act."

She said the suspect, an ethnic Uyghur, also injured himself and was caught on the scene, adding that police are investigating his motive.

All the casualties were local residents, Hou said, and authorities are still verifying their identities and ethnic backgrounds. Officials at Aksu No. 1 People's Hospital, where the injured are believed to have been sent, declined to comment.

Long-simmering ethnic tensions between Han Chinese and native Uyghurs in Xinjiang, who are Turkic-speaking Muslims, erupted into street riots in the provincial capital of Urumqi in July 2009, killing almost 200 people and injuring more than 1,800.

Authorities have blamed independence-seeking Uyghur groups for the worst ethnic violence in recent Chinese history. The government has since increased its crackdown on so-called "separatist terrorists" and announced last July the breakup of a bomb-making ring in southern Xinjiang.