JINAN, Jan. 9 (Xinhua) -- Police in east China's Shandong Province said Saturday that one of the two killers who shot dead four policemen on Jan. 4 had also murdered another man before the gunfight.

Liu Jianjun, 50, allegedly killed one man on Dec. 29 last year in Dezhou City of Shandong.

Liu and his 52-year-old brother Liu Lumin shot at policemen who were investigating the Dec. 29 murder case in Tai'an City of the province on Jan. 4 .

Three policemen were killed at the scene, and another died later in the hospital.

After gunning down the officers, the two men fled the scene, hijacking four cars and shooting two drivers before their car collided with a police wagon.

The gunmen, armed with a homemade pistol and a double-barreled shotgun, continued to fire after police had cornered them, injuring more policemen and civilians.

Liu Lumin then shot and killed himself while Liu Jianjun was taken into custody.