A man killed himself after shooting three judges dead and injuring another three judges in a local court office Tuesday in central China's Hunan Province, local authorities said.

?Photo taken on June 1, 2010 shows the Lingling District People's Court in Yongzhou City, central China's Hunan Province.

The incident happened at about 10:05 a.m. at Lingling District People's Court in Yongzhou City, said the city's public security department.

The gunman, Zhu Jun, barged into an office on the fourth floor of the court building. He shot the judges in the office before killing himself, police said.

One critically injured judge was still under emergency treatment and another was in serious but stable condition. The third was slightly injured.

Zhu, 46, was head of the security squad of the China Post branch bureau of Lingling District.

Around 7:30 a.m., Zhu took a submachine gun and two pistols from his subordinate, saying he would have the guns examined by the higher authorities, police said.

Zhu, who had a son, divorced his wife in 2003. He lived with his parents, initial police investigation showed.

In 2006, Zhu filed a real estate transaction case to the Lingling District People's Court. Although Zhu won the case, he was not satisfied with the execution of the verdict.

The investigation said Zhu had suffered from nasopharyngeal cancer since 2006, which turned terminal this year. He was believed to become resentful and suicidal due to the lawsuit, his divorce and his illness.

Zhu was on sick leave at home for two months and only came back to work three days ago, police said.

Special police and procuratorial task forces were set up for further investigation. Three officers in charge of firearms administration involved in the case were currently under investigation, according to local authorities.