Investigators are still looking into the cause of Sunday's bus fire in Darien, CT. 

The driver of the DATTCO charter that was heading to Fall River said the heat stopped working on the bus before the fire.  Once the heat shut off, the driver said he was heading to the first rest stop, but there was a loud noise and black smoke started coming from the back of the vehicle. 

The bus was traveling along I-95 amid a winter storm that prompted officials to declare a travel ban for state highways.