Twelve Oxon Hill Middle School students and their bus driver were injured — though not seriously — after a work mini-van crashed into their bus Monday morning, authorities said. The driver of the work van was critically hurt.

The incident occurred about 8:15 a.m. in the 8300 block of Indian Head Highway, said Cpl. Mike Rodriguez, a Prince George’s County Police spokesman. He said the bus was on a service road that runs perpendicular to the highway when the work mini-van crashed into the back portion of it on its driver’s side. The van — which had been headed north on Indian Head Highway before turning onto the service road — then crashed head-on into a tree, Rodriguez said.

Rodriguez said the driver of the mini-van was the most seriously hurt and was flown to a nearby hospital in critical condition. Twelve students and the bus driver were also taken to the hospital for treatment of minor injuries, Rodriguez said.

Investigators are still probing why the mini-van veered on to the service road and why it hit the bus, Rodriguez said.