China's state news service says two people were wounded by a bomb outside government headquarters in the northeastern city of Tianjin. It said the attacker sought revenge over personal problems.
The official Xinhua News Agency said Saturday that one man was arrested on suspicion of setting off the explosion just before 10 a.m. (0200 GMT) Friday.
It said the suspect, a Tianjin resident identified only by the surname Liu, had been having problems with gambling and family members and wanted "revenge against society."
Last month, a man described as upset over a land dispute with the government set off three bombs in the southern city of Fuzhou, killing himself and two others and stirring a public angry at official corruption and indifference.