Yang Jia, the man who allegedly killed six police and injured another four here last week, was formally charged and put under arrest for the crime, the Shanghai People's Procuratorate announced on Monday.

Yang had been held in police custody since the incident.

"Yang is suspected of murder. He violated the law, and the social effect of his premeditated ferocity is very bad," said an official with the procuratorate.

The 28-year-old unemployed man from Beijing stabbed a security guard at a police branch in the Zhabei district of Shanghai on the morning of July 1 and started a fire at the gate of the facility, before charging into the building and attacking nine officers.

Revenge for a lengthy interrogation last year was cited as the cause of the stabbing spree, according to authorities with local police.

(Xinhua News Agency July 8, 2008)