Sound Transit's 522 bus that arrives at 6th and union at approximately 5:40 blew a tire immediately upon its first downtown stop.
The exploded tire sounded like an explosion and was immediately followed by smoke. I originally thought we'd been rear ended.
The driver directed people to get off the bus and upon doing so, someone yelled 'fire'. Everyone got off and as we were doing so, a second tire exploded. These explosions were loud and sounded like bombs.
After the second explosion, the driver came out with a handheld fire extinguisher and a few other businesses came out with extinguishers and sprayed the tire well.
I think it was a poor decision considering that there were contents under pressure on fire and that the distance required to correctly operate the extinguisher put you at risk for explosion related injury.
The fire truck was there within 3 minutes of people getting off the bus and I didn't stick around to watch the resolution, as I had to be at work, which was 20 blocks away.

irknotme says ...
On Thursday, Dec 10 at 1:46 PM
Given that there are only two tires and both had discharged their contents (air) there was minimal danger to those that put out the fire. FWIW, they probably saved us tax payers the replacement cost of a new bus.