The fatal crash happened on a busy stretch of PCH near Lemon Avenue.
Two northbound lanes were blocked while an investigation was conducted into the circumstances of the crash.
The motorcycle was found down just before 5 a.m., which led to the discovery of the deceased motorcyclist nearby.
The crash occurred at 7:25 a.m. Saturday near the 710 and 405 freeways.
The vehicle became engulfed in flames and the victim was trapped inside, the CHP said.
The woman who was killed was a passenger in one of the vehicles involved in the collision at around 1:42 a.m. at the intersection of Pacific Avenue and 21st Street, authorities said.
Long Beach police said the man was operating the ATV “at a high rate of speed when he possibly lost control and fell from the vehicle” at about 7 p.m. at the river channel near Wardlow Road.
One woman was pronounced dead at the scene, and a man was transported to the hospital, said police.
Joseph Maez, 26, entered his plea to one felony count each of gross vehicular manslaughter while intoxicated, driving under the influence of alcohol causing injury and driving with a 0.08% blood-alcohol content causing injury, according to the Los Angeles County District Attorney’s Office.
Police said speed may have been a factor in the crash, but it is not believed that driving under the influence nor distracted driving played a role.