( CNN ) -- An Oakland , California , police officer critically injured in one of two Saturday shootings that killed three fellow officers was pronounced brain dead on Sunday , a police spokesman told CNN . Clockwise from top left : John Hege , Sgt . Daniel Sakai , Sgt . Ervin Romans and Sgt . Mark Dunakin . Initially , Oakland police spokesman Jeff Thomason said John Hege , 41 , was the fourth officer to die after a man being pulled over in a traffic stop opened fire and then battled SWAT officers at a nearby building Saturday . However , Thomason clarified later Sunday that Hege was pronounced brain dead about noon Sunday , but being kept on life support until a decision is made on organ donation . The man who police said was the gunman -- Lovelle Mixon , 26 , of Oakland -- was fatally shot in a gunbattle with SWAT officers in an apartment complex Saturday . Police said in a late-night news conference Saturday that Mixon had an extensive criminal history and was in violation of parole for assault with a deadly weapon . He also had prior convictions in Alameda County for grand theft and possession of marijuana , the Oakland Tribune newspaper reported . The city of Oakland is in Alameda County . Watch report from CNN 's Kara Finnstrom » . The incident began about 1 p.m. Saturday in east Oakland when two motorcycle officers tried to pull over a car for a `` fairly routine traffic stop , '' said Dave Kozicki , the deputy police chief . Watch fellow officers , families grieve » . Emergency call dispatchers then received reports that two officers were shot and needed help , he said . Those officers were Hege and Sgt . Mark Dunakin , 40 , an 18-year veteran of the force , who died Saturday . Watch acting police chief describe what happened » . Soon after the first shooting , police began an intense search for the gunman . An anonymous caller directed authorities to a building on an adjacent street where the gunman was believed to be barricaded , acting Police Chief Howard Jordan said . Watch aerial views of shooting locations » . The gunman opened fire on SWAT officers who entered the apartment , killing two officers before police returned fire and killed the suspect , Jordan said . Those two slain police officers were Sgt . Ervin Romans , 43 , and Sgt . Daniel Sakai , 35 . Romans had been with the department since 1996 ; Sakai since 2000 . A fifth officer was grazed by a bullet . He was treated and released , Thomason said Saturday . In a statement , California Gov . Arnold Schwarzenegger called it `` a tragic day for law enforcement officers everywhere . '' Watch the community give support » . `` All four officers dedicated their lives to public safety and selflessly worked to protect the people of Oakland , '' Schwarzenegger said . In honor of the officers , he said , flags at the state Capitol would be flown at half-staff . CNN 's Janet DiGiacomo and Faith Karimi contributed to this report .
NEW : Police officer being kept on life support until decision on organs made . Three of his fellow officers killed in shootings in Oakland , California . Shootings occurred in two different locations in Oakland neighborhood . Suspect died in exchange of gunfire with police , police say .