On December 14, 2012, a gunman killed twenty children and six adults at an elementary school in Newtown, Connecticut.
The United States experienced several mass killings in 2012, including the Colorado cinema shooting in July that killed 12 people and injured nearly 60 others. In August, a killing spree at a Sikh temple left seven people dead.
Every year, more than 30,000 people are shot and killed in the US.
At least four people have been killed and several others wounded in a shooting spree in the US state of California.
On Tuesday, police sources said the shooting spree through Orange County went on for 25 minutes, ending with the gunman killing himself.
Orange County sheriff’s spokesman Jim Amormino said that there were at least six crime scenes. Tustin police received reports of the shooting shortly after 5 a.m. local time.
One of the victims was found at State Route 55 and McFadden Street. Another was killed at Del Amo Boulevard and Edinger Avenue. Two were also shot and wounded at Interstate 5 and Red Hill Avenue.
The shooter killed himself at the intersection of Wanda Road and Katella Avenue.
Reports say the shooting started after an apparent carjacking.