TIS...I'm not sure how, but he was hit by the rear of the bus, according to the detailed article posted above by plawrence. The driver had no idea what happened and apparently drove off...a witness took down the plate #.
It was ruled an accident.

We can all say 'damn driver'...but imagine how this poor guy must feel, having to now live with the knowledge that the vehicle he was driving killed anybody, let alone an elderly actor best known for a role in an American classic.

Apple