A Chicago bus driver taking students from Rowe Elementary School to a field trip at Northwestern University told police he was momentarily distracted before rear-ending another bus from the school in a crash that sent 20 students and an adult to three area hospitals Tuesday morning, authorities said.

The accident happened at about 11:15 a.m. in Evanston while the buses were northbound on Chicago Avenue, near Davis Street, officials said. There were 24 students on one bus and 26 on the other.

The driver in the rear bus may have been looking at his side mirror when the accident happened, according to Evanston Police Commander Tom Guenther.

One victim complained of chest pains while others suffered neck and lower back pain, said Evanston Fire Chief Greg Kaiber. None of the injuries appeared to be life-threatening, Klaiber added.

They were taken to Evanston Hospital, Skokie Hospital and St. Francis Hospital by ambulances from Evanston, Winnetka, Wilmette and several other communities, Klaiber said.

All of the injured passengers were released from area hospitals by 5:30 p.m. Tuesday, hospital officials said.

Nine passengers were taken by ambulance to St. Francis Hospital, and two came later on their own, hospital officials said. Six of the patients – all middle school students – were treated to a cookout on the lawn outside the hospital after they were released. The cookout, according to officials, was part of a three-day event at the hospital honoring the area’s emergency medical personnel.

Thirteen patients were seen at Evanston Hospital and Skokie Hospital, and all have been released, officials said.

Some of the students who were not injured were taken to an insurance agency near the scene of the accident.

“The kids said it was a huge ‘boom,’” said Brittany Benson, an employee at the agency. “When they first came in, they seemed scared … But they calmed down quickly.”

“The accident didn’t look all that bad,” said Mallory Blackburn, an employee at Nail Bar, a salon near the scene. “The back window (of the lead bus) was smashed out.”

Blackburn has worked at the salon for three years.

“There’s always some kind of accident at that intersection,” she said. “Whenever there’s something big, it’s always around here.”

The students who were not injured continued on with their field trip, according to Klaiber.