TEMECULA -- A Temecula Valley High School student was stabbed in the upper body Friday, in front of dozens of other students across the street from the campus.

As paramedics treated the teen at the corner of Margarita and Rancho Vista roads, students, parents and school officials scrambled around -- some visibly upset and others on cell phones describing the scene.

The attack happened just before 3 p.m. along a sidewalk near the Rancho California Sports Park.

Michael Lacy Jr., 16, was stabbed three or four times in the chest and stomach, Temecula police Sgt. Mark Lohman said. A 16-year-old boy was arrested about an hour later on suspicion of assault with a deadly weapon.

Investigators said the attack may have been in retaliation for a fight earlier in the day at a different location. Police said the suspect does not attend Temecula Valley High, but goes to a continuation school in the area.

Witnesses told police that the assailant appeared to just walk up and stab the victim, officers said.

Lacy was taken by ambulance to Inland Valley Medical Center in Wildomar, where he was taken into surgery about 4 p.m., Lohman said. His condition was unavailable late Friday. About the same time that was happening, police were getting ready to arrest the teen suspected of the assault.

Officers at the stabbing scene were able to get a name and description of the assailant and went to the apartment where the boy lives on Mira Loma Drive. He wasn't there, but they told a relative to call if he returned.

Just after 4 p.m., police received a call from the suspect saying he was there, so two officers went back and arrested him. His name has not been released because of his age.

The teen told officers he may have broken a thumb at the time of the assault, so he was taken to Rancho Springs Medical Center in Murrieta for treatment before being booked at Southwest Juvenile Hall in French Valley, the sergeant said.

Students who witnessed the attack were taken back to the nearby high school where school officials had them write down what they saw to later be collected by police.

Not long after the attack, Lohman said, some children found a knife on Argo Court, one street west of where the teen was stabbed. Investigators recovered the knife and believe it was the one used. The weapon was described as a folding knife with a blade about four or five inches long, Lohman said.

Hours after the stabbing, forensic technicians from the Riverside County Sheriff's Department were at the scene taking photos and collecting evidence, including a bag of bloody clothing left there by medical personnel who treated the injured boy.

Contact staff writer John Hall at (909) 676-4315, Ext. 2628, or jhall@californian.com.