Officer Anton Fischer, a three-year veteran of the Long Beach Police Department, crashed with another vehicle in the area of 7th Place and Ocean Boulevard at about 2:25 p.m., according to police.
Fischer sustained "substantial injuries'' and was transported to a hospital, where he died.
"The preliminary investigation indicates that the motorcyclist was traveling eastbound on Ocean Boulevard when the driver of a 2011 Jeep Grand Cherokee made a left turn from 7th Place to westbound Ocean Avenue," police said. "The motorcyclist was unable to stop in time and struck the side of the Jeep."
Police said the driver of the Jeep remained at the scene and is cooperating with the investigation.
"We are saddened by the death of Long Beach Police Officer Anton Fischer at the age of 33," Mayor Robert Garcia said in a tweet. "He died in a traffic accident today in our city. We are grateful for his service and dedication to our community. Please keep Officer Fischer's family and friends in your thoughts."