"It vowed to "ensure the issue is investigated and dealt with according to our internal procedures"."

A really poor statement, and one that makes no confirmation that the driver is OK. It's of course not a rational thing to do, but it could be as the result of trauma or something else that has mentally tipped them over the edge. 

Sounds like the disciplinary handbook is instead out, rather than understanding the events what led up to the incident, but maybe the internal culture plays a big part...