A woman is in critical condition following a Monday morning bus crash involving a school bus with the Mercedes Independent School District, according to the Mercedes Police Department.

Occupants on the bus, which included one student, did not sustain any injuries, according to a news release.

The bus was at a stop sign, signaling to turn into the bus entrance at Sgt. William G. Harrell Middle School, when it was rear ended by another vehicle. 

The vehicle, driven by an unidentified 45-year-old, was halfway under the rear of the bus. It is still unknown what caused the driver to rear-end the bus, according to the news release.

This is a developing story. Check back for updates.