HURRICANE, W.Va. (AP) — Seven students were injured Wednesday morning when a West Virginia school bus hit a tree, officials said.

One student was in serious condition and will need surgery due to internal injuries, but the other injuries appeared to be minor, Putnam County Sheriff Bobby Eggleton told news outlets.

It appears the bus driver experienced a medical emergency that led to the crash, Eggleton said. The driver also was taken to the hospital, but an updated condition wasn’t available.

The children appeared to be elementary school students, officials said.