Two Montgomery County students spilled out of a bus on their way to school Wednesday morning after their bus went over a bump and the door to an emergency exit flew open.

Authorities say an unusual chain of events led to the incident, in which the boys suffered minor injuries.

Two 5- and 6-year-old boys were on their way to Takoma Park Elementary School when the strap of a student’s backpack got caught on the latch of an emergency exit door on the side of the bus, said Montgomery schools spokesman Dana Tofig.

As the bus was turning, it went over a bump, the backpack strap lifted the latch, and the door flew open — causing the students to fall out.

The students were taken to the hospital but did not appear to have serious injuries, Tofig said.

The school system conducted an investigation, the spokesman said, and “it does not appear that anything was malfunctioning.”

“It was a very rare set of circumstances.”