SHIJIAZHUANG - A man allegedly murdered a family of four, including a 7-year-old boy, before killing himself on Saturday night in North China's Hebei province, local police said.

A 60-year-old surnamed Zhao visited the home of a man surnamed Zan in the city of Botou at 9 pm, killing Zan, his wife, daughter-in-law and grandson with a hammer and a kitchen knife, according to the city's public security bureau.

Zhao later telephoned his family and said he "had vengeance" before committing suicide at the site of the murder, police said.

Zhao's son is the ex-husband of Zan's daughter, and the two families have been embroiled in a divorce dispute, police said, adding that an investigation is under way.