Torrance police said the incident happened at Switzer Learning Center, a nonpublic school that specializes in educating students with learning differences, according to the school's website.
Two of the victims were rushed to a hospital in critical condition. A news release later said their conditions were not life-threatening. A third victim was treated at the scene by Torrance Fire Department paramedics for minor injuries. The suspect allegedly attempted to stab a fourth staff member before fleeing the scene.
Video from AIR7 showed what appeared to be a backpack and knife on the ground near the school, located on Amapola Court.
"Following the incident, the suspect was taken into custody by Torrance Police without further incident," the news release said. "During the apprehension, the suspect made statements indicating he had placed two pipe bombs in the vicinity of 208 Street and Amapola Avenue."
The Los Angeles County Sheriff's Department's bomb squad was summoned to the area to investigate. Members of the public were urged to avoid the area of 208 Street and Amapola Avenue, which is just southwest of the Switzer Learning Center campus.
Torrance police said two objects were located, and they were determined to be incendiary devices, which was rendered safe by the Los Angeles County Sheriff's Department's bomb squad.
The suspect's name was not immediately released. The incident is under investigation.
The stabbing suspect allegedly has ties to an apartment unit in Redondo Beach. Investigators conducted a search there, and video showed a robot from the sheriff's bomb unit climb the stairs.
Dan Lankford lives nearby. He snapped images of a sheriff's helicopter landing at a nearby park and dozens of officers in tactical gear swarm his community and surround the apartment building.
Neighbors say the scene in Redondo Beach was tied to the one four miles away at Switzer Learning Center.
Anyone with information about the case is urged to call the Torrance Police Department at (310) 328-3456.