Los Angeles, CA, USA — 2012-07-23 ~5pm — corner of Victory Blvd & Owensmouth Ave near Best Buy and Westfield Topanga Mall.
Accident back story (alleged): Car A (not pictured) turned left in front of Car B (the wet one) and crashed, sending Car B into mounted position on top of fire hydrant. Wetness ensues. No major injuries reported.
The water gushed for probably 30 minutes or more, spraying with incredible force and volume across two lanes of traffic, giving free car washes to hundreds of vehicles as they waited for the light to turn.
You can see in this video a fireman working his pickaxe, breaking a small hole in the street at just the right spot, which was subsequently penetrated with a giant two man wrench by which they managed to shut off the flow of water.
Shot with iPhone 4 close enough that my feet got wet.