A 13-year-old boy was killed and a 9-year-old girl was airlifted to Children's Medical Center in Dallas after a school bus and Union Pacific train collided in Athens, Texas, Friday afternoon.

Superintendent Blake Stiles asked for prayers.

"I've been in this profession for 21 years, this is by far the worst day," he said. "Our hearts are broken for the families… and everyone involved in the accident."

Names of the students and driver were not immediately released.

Kenneth Farmer owns a bail bond company a block away.

"Walked to the road and saw the train and thought 'Oh my goodness,'" he said.

Farmer said emergency crews spoke to the driver and asked if he was OK.

"Well I feel angry at myself," Farmer quoted the driver as saying. "And he said, 'I stopped and looked, there was nothing coming ... When I began to cross the tracks, I looked up and there was the train.'"

A prayer service was held Friday night at United Methodist Church in Athens.

The district said the girl who was injuured attends Central Athens Elementary and was in critical but stable condition.

The bus driver, whose name has not yet been released, was taken by ground ambulance to a nearby hospital.

The cause of the crash is not clear.

The Athens Police Chief said the bus and train came to a stop about a quarter-mile from the impact location. He also indicated that the railroad crossing does not have any flashing lights or arms.

The Athens ISD has canceled all athletic events planned for Friday night.

Union Pacific Railroad released a statement about the crash on Friday night saying "We are currently working to clear the tracks, and we continue to work with the Athens Police Department to determine why the bus was on the tracks. Our investigation team is walking the track, checking the signage and signal boxes for all the crossings in the area, as well as reviewing video from the outward-facing camera. This is standard procedure. The Athens Chief of Police will provide information about those involved in the incident."