Police received a report at 11:58 a.m. of a flurry of fights that broke out during a lunch break at the school, located at 1633 East Ave., police Lt. Roger Keener said.
The incident began when the Hayward police school resource officer assigned to Hayward High School responded to a fight between a male and female student.
As the two students were separated, another fight broke out in the same area between two female students, Keener said.
As the officer stepped in to stop that fight, a male student tried to punch the officer. Several smaller altercations ensued, prompting the officer to ask for assistance from other officers.
Hayward police, Alameda County sheriff's deputies and California Highway Patrol officers responded to assist at the school.
Six students were eventually arrested, some on suspicion of fighting on school grounds and others for interfering with police, Keener said.
No weapons were reported in any of the fights, and no one was seriously injured, he said.