Medics attended 29 passengers for injuries, with four of them reported to be in serious condition. The driver fled the scene, according to police.
The 40-seat Volvo bus was full when the fire started at 5:20 p.m. on an inbound Guadalajara lane near El Tapatio Hotel. Many of the workers had dozed off.
A short circuit is believed to have caused the flash fire, which spread rapidly through the bus, which was owned and operated by a private firm. Many of the startled passengers were forced to break windows to escape the vehicle.
Once firefighters arrived, it took only minutes to douse the flames, although the bus had been completely destroyed.