Footage from inside the bus shows the driver removing the brakes, then rear ending another vehicle twice before careening into the brownstone building Monday.
He also appears to have narrowly missed at least one other occupied car.
A row of parked cars got in his way.
A total of 16 people were hurt, but fortunately most left with minor injuries.
The MTA says the crash does not look like it was caused by mechanical error.
The exact cause is still being determined, but senior officials believe actions by the driver will end up being the cause.
They say the driver may have been distracted, or his foot may have gotten stuck between pedals.
Investigators are citing numerous apparent violations, including the bus driver using a phone while driving, stopping the bus in the middle of the route and opening the protective barrier and leaving his seat.
They say he also then deactivated the bus brake before closing the barrier or buckling his seat belt and had two bags in the bus driver area while driving -- one of them was at his feet.
"The video is disturbing on many levels, raising questions about whether basic safety rules were followed. The incident remains under investigation and we will have more to say when that is complete," said Tim Minton with the MTA.
"Thank God that nobody got killed," neighbor Corey Demetrio said. "It literally went through somebody's house."
The 55-year-old driver, who has been on the job for 13 years, wasn't seriously injured. Officials say he has no major safety record infractions, only minor collisions.
The bus remains in the brownstone at 174 Lincoln Road Wednesday, after the Department of Buildings determined the structural stability is compromised and the building is no longer safe to occupy.
The Buildings Department says before the bus can be removed, the building owner must install shoring to prevent a potential collapse.
All residents in the building have been offered emergency relocation assistance.
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