Beijing police have seized a man who was suspected of setting off an explosion in downtown Beijing's diplomatic area last week.

Lei Sen, 21, confessed he had caused the blast "for personal reasons", Beijing Public Security Bureau said in a press release Wednesday night.

It said Lei, from Nanchong City in the southwestern Sichuan Province, was captured on the same day.

But the document did not say how or where he was caught.

The blast occurred on Oct. 21 near the busy Dongzhimen subway station, close to many embassies.

A 30-year-old American man who was studying in China was slightly injured in the leg.