CAMPO, Calif. — No one was hurt when a man armed with a knife entered a school bus with children on board on Friday, authorities said.

The incident occurred at about 8:30 a.m. at a school bus stop in Campo, a small town just north of the U.S.-Mexico border.

According to the San Diego County Sheriff’s Department, elementary students had boarded the bus at an apartment complex, and then the bus driver closed the door and started to pull forward when he noticed a man running toward the bus. The bus driver said he believed that the man was a father trying to stop the bus for a child running late, so the driver stopped and opened the door.

Deputies said that the man entered the doorway of the bus, and the driver told him he could not come on board, but the man continued up the stairs of the bus.

According to the Sheriff’s Department, the school bus driver tried to stop the man from moving back toward the children, and the man struggled to push by him and allegedly pulled out a knife.

Meanwhile, deputies said that an older student ushered the other passengers toward the back of the bus and called out for help to parents who were still nearby.

“The emergency door at the rear of the bus was opened and the children were able to get off the bus unharmed,” the Sheriff’s Department said.

During the struggle, a grandmother of one of the students saw what was happening and boarded the bus to help the driver. Deputies said that another person got on board and heard the driver yell that the man had a knife to his head. The “good Samaritan,” as the Sheriff’s Department described him, reportedly pried the knife away from the man and pulled him off of the bus as deputies were arriving.

Deputies arrested suspect Matthew D. Barker, 37, without further incident. Barker faces felony charges of assault. The Sheriff’s Department said that drugs are believed to be a factor in the incident, and the investigation is ongoing.

The Sheriff’s Department said that no one involved in the incident was injured.