ALDEN, N.Y. (WIVB) — A school bus erupted with thick, black smoke as it caught fire at a Crittenden Road bus garage in Alden Wednesday morning.

A stationary bus caught fire in the transportation lot of Alden Central School District, officials said. First responders were immediately called to the scene. It is not clear what caused the fire, but the Erie County Sheriff’s Office continues to investigate.

School officials say the bus wasn’t routinely used and hadn’t actually been on the road in a month.