TORONTO -- The Toronto Transit Commission says most of its 153 extra-long articulated buses that had to be repaired through the night because of a problem with "unexpected acceleration" are back in service.

The TTC had pulled the 18-metre long buses off the roads after two of the vehicles experienced a "full throttle" situation.

It happened to one bus during routine maintenance and the other as it was being driven back to a garage, forcing the driver to quickly regain control of the vehicle

No customers were on either bus and no injuries were reported.

The TTC said the glitch was being repaired thanks to a software fix from Nova, the bus manufacturer.

TTC spokesman Brad Ross tweeted this morning that just over 100 of 153 buses had been returned to service.