The Chicago Police Department released the driver who was in custody after Friday’s fatal L station accident. Donald Wells was cited with negligent driving after plowing a semi-trailer up the escalator of a Chicago Transit Authority train stop. The crash killed two people and injured at least 21 others.

It’s still unclear why driver Donald Wells crashed his rig into the Cermak-Chinatown Red Line station. Authorities say his blood-alcohol test was negative, and police continue to investigate Friday’s accident. Wells faces a maximum fine of $100 if convicted of negligent driving, but more charges are possible.

Service at the train station resumed on Saturday, and passengers are using an auxiliary entrance to reach the platform. A CTA spokeswoman did not know when repairs would be completed.