Three people were injured after a detonator exploded Tuesday in a court office in southwest China's Guizhou Province, according to local police.

Wu Yongfa, 74, set off a detonator in an office of the People's Court of Yunyan District in Guiyang City, the provincial capital, injuring himself and two judges, a police spokesman said.

Wu, who was not satisfied with the support his four grown-up children were providing him, asked the judges to summon his children to the court before the explosion, a court spokesman said.

It's not immediately clear why Wu set off the detonator. Police investigation is underway.

A court verdict ruled that each of his children should provide him 100 yuan (14.6 U.S. dollars) per month starting May 2008. The children duely paid the money.

Criminal record showed that Wu once threatened his ex-wife and children with a detonator in 2007 over financial disputes. Although the explosives didn't go off, Wu was sentenced to three years in prison by the same court.