The blast occurred outside a branch of China Construction Bank at about 5:35pm (0935 GMT) in Hongshan district of Wuhan, the capital of Hubei province, the official Xinhua news agency said.
An initial police investigation showed the explosion was triggered by an unidentified object outside a nearby drugstore, it said.
Fire department spokesman Tian Jingchao said on the Twitter-like weibo site that the blast came during an attempted robbery.
Xinhua, which made no mention of a robbery, said two passers-by were killed and the injured were sent to nearby hospitals, although their conditions are not known.
Wuhan police reached by telephone declined to give further details.
In May, the government said that arson had caused an explosion at a bank in rural northwest Gansu province that injured 49 people, Xinhua reported earlier. (*)
Editor: Kunto Wibisono
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