The explosion occurred at a branch of China Construction Bank at about 5:35pm (0935 GMT), the local fire department in Wuhan, Hubei province, said on its Twitter-like weibo account.
Police ruled out a gas leak as a possible cause of the explosion and have blocked roads around the bank, the official Xinhua news agency said, adding that roads around the bank had been blocked.
Fire department spokesman Tian Jingchao said on weibo that the blast occurred during an attempted robbery and a local provincial newspaper's weibo said that the explosion had hit an armoured bank truck.
However, the robbery was not mentioned in the account of the blast published by the official China News Service, which said one person was killed and six were injured.
Police were investigating the incident, said Xinhua, which made no mention of any deaths.
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 northwestern China's Gansu province that injured 49 people, Xinhua reported earlier.