As reported to the FAA. Reports are unverified, and codes are left as the FAA publishes them.
What was found
THE AIRCRAFTS CABIN AND COCKPIT FILLED UP WITH SMOKE DURING TAXI ON THE RAMP. THEY STOPPED AND EVACUATED THE PASSENGERS THROUGH THE MAIN CABIN DOOR ONTO THE RAMP. MAINTENANCE INSPECTED THE AIRCRAFT AND DISCOVERED THAT THE LH AIRCONDITIONING PACK CAUSED THE ISSUE AND WE DEFERRED THE LH AIRCONDITIONING PACK AND THE AIRCRAFT WAS RETURNED TO SERVICE.