The break led to a massive shower of rocks and water, which caused damage to nearby cars, but some say it could have been a lot worse.
The damaged vehicles are testimony to what happened in Belvedere early Wednesday morning -- from a Mercedes coated in rock and debris, to a BMW with a busted-out window. One neighbor said it sounded like a massive hailstorm -- loud and sudden.
"In the middle of the night, there was this big thump, and I went back to sleep, so this morning I was surprised that half the street was covered with dirt and mud," said neighbor Bob Heller.
The two luxury cars weren't the only ones that were damaged.
"A total of ten cars that were here in the area. Because it was the middle of the night we didn't have a very good description of what the damage was," said Belvedere police chief Tricia Seyler.
On the one hand, if it happened in daytime, someone might have been outside and injured by the close-to-rock shower. On the other hand, had the pipe broken in a different location, there might have been no damage at all.
"We don't know what caused it, but what happened is the pipe had a break -- a hole in the top of the pipe," said Libby Pischel with the Marin Municipal Water District. "It was a lot of force and it caused the asphalt and concrete and everything else to come up with it."
The pipeline is 40 years old and is the one connecting the water main with a hydrant, so there was no water service lost to residents. The hydrant won't be available for duty until repairs are done.
The contractor charged with fixing the street might take days to get Maybridge Lane back to the way it was until about three Wednesday morning.
Seyler says police will continue to investigate the damage. The bill for the damage caused to cars and homes will go to the water district.