A Chicago fire truck heading to a call collided with an empty school bus Friday morning, killing one firefighter and injuring three others. The bus driver had just finished dropping off the children for the day.

Witnesses reported that the fire truck's lights and siren were on but that the bus driver couldn't stop in time. The impact knocked the truck on its side, police spokeswoman Laura Kubiak said.

Firefighter William Grant, a 44-year-old father of three, was killed, said Chicago Fire Department spokesman Richard Rosado.

Fire Commissioner Raymond Orozco said Grant's death was "a loss to all of us."

The conditions of the injured firefighters and the bus driver were not immediately released.

The bus was operated by a contractor, Chicago Public Schools spokesman Mike Vaughn said. He said the driver had just dropped off students at Sheridan Elementary School, about four miles north of the accident on the city's South Side.