Six people were killed in a drive-by shooting at a university campus in southern California overnight Friday, in what police called "mass murder". The gunman also died after exchanging fire with police, authorities said. It was not clear whether the fatal gunshot was self-inflicted or delivered by police. Driving a black BMW, the suspect opened fire on pedestrians from his vehicle at several locations in the town of Isla Vista in Santa Barbara on a busy Friday night. Police are "analyzing both written and videotaped evidence that suggest this atrocity was a premeditated mass murder," Santa Barbara County Sheriff Bill Brown told a press conference. "We have identified nine separate crime scenes," Brown said, describing the situation in the streets of the college town as "chaotic". TV footage showed ambulances and police cars swarming the campus. Authorities believe the shooter acted alone and are investigating a threatening video posted by the alleged gunman on YouTube. They have not yet released the suspect's name. The shooter twice exchanged gunfire with police from his car before crashing into a parked vehicle. When police approached him, the suspect "was dead of an apparent gunshot wound to the head," Brown said. Police said they recovered a handgun from the suspect's vehicle. The shooting hit as the academic year was winding down, with some students preparing for graduation ceremonies, while others were about to take final exams. School shootings have become a tragic periodic occurrence in the United States in recent years, from the December 2012 massacre at Newtown, Connecticut that left 20 small children dead to the Virginia Tech college shooting in April 2007 in which 33 people, including the lone gunman, lost their lives.