LAPD: California mother killed boyfriend and baby before crashing truck into tree and dying

A California mother allegedly stabbed her boyfriend to death and threw her daughters from a moving vehicle, resulting in the death of her 8-month-old baby, before crashing into a tree in a murder-suicide case.

Police learned of the chaos when they found an 8-month-old baby and a 9-year-old girl in the middle of the 405 Freeway in Los Angeles around 4:30 a.m. of Monday.

The baby was pronounced dead at the scene, but her older sister managed to survive the fall with “moderate injuries,” according to the Los Angeles Police Department.

Half an hour after the discovery, the children's mother, Danielle Johnson, was found dead in her crushed vehicle several miles away in Redondo Beach.

Johnson, 34, had been driving his pickup truck at speeds exceeding 100 mph when he hit the tree, the department added. It is not yet known whether the accident was intentional or unintentional.

Three hours later, investigators discovered the body of Jaelen Aleen Chaney, 29, in the luxurious Woodland Hills apartment she shared with Johnson and her daughters.

Neighbors called 911 after seeing a trail of blood in the hallway leading to the couple's apartment door, which was open.

Johnson allegedly stabbed Chaney to death during a verbal argument around 3:40 a.m. She then loaded her two daughters into the van and drove through the apartment complex's security gate.

That's when he headed toward the road, where “the minors fell or were thrown out of the moving vehicle,” according to the California Highway Patrol.

The motive for the murder-suicide is still unclear. Investigators are working to determine if the baby had died before being thrown from the car.