A limousine service operator was charged Wednesday with criminally negligent homicide in a crash that killed 20 people, while police continued investigating what caused the wreck and whether anyone else will face charges.

Nauman Hussain, 28, showed little emotion as he was arraigned Wednesday evening in an Albany-area court, and he ignored shouted questions from reporters as he left after posting $150,000 bond. A judge had entered a not guilty plea for him.

The driver of the limousine, Scott Lisinicchia, also died after he missed a stop sign at a T-intersection and the vehicle plowed into an SUV parked outside a store. The crash also killed two pedestrians and all 17 passengers.

State Police and the National Transportation Safety Board are investigating the cause of the crash, the nation’s deadliest transportation collision since Colgan Air Flight 3407 went down outside Buffalo in February 2009, killing 50 people.