A school resource officer used pepper spray to break up a crowd of students after two fights erupted Monday at Como Park Senior High School in St. Paul.

According to police, two girls, ages 14 and 15, started fighting around 10 a.m. When an assistant principal tried to intervene, he was pushed from behind and fell. As a large group of students gathered to watch the fight, a second fight broke out between two more girls, ages 14 and 15.

The school resource officer on duty then sprayed a short burst of pepper spray into the air. The four girls were arrested on suspicion of assault and riot; a boy was later arrested on suspicion of disorderly conduct after he complained to the school office about how the incident was handled and began throwing things, said Sgt. Paul Paulos, a St. Paul police spokesman. No students were injured, he said.

School officials later notified — by letter and with a telephone call — families of all Como students about the incident, said Toya Stewart Downey, spokeswoman for the school district.

NICOLE NORFLEET