The blast, which shook around 7 a.m., was so strong a witness reported seeing a manhole cover propel several feet into the air and shoot through the window of a business.
The incident forced the closure of the area near the 4400 block of Slauson Avenue and Angeles Vista Boulevard in the Windsor Hills area of Los Angeles.
Business owners and workers rushed to the scene minutes after the explosion.
"I jumped in the car and ran over here and lo and behold, all my windows are all blown out, windows down the side all blown out," said business owner Robert Brimm. "My next door neighbor, their windows were all blown out."
Despite the damage caused to businesses, owners are grateful the incident occurred on a Sunday instead of during the busy work week where customer traffic is at an all-time high.
Kevin Smiley, a W.H. Sharpening employee, believes the aftermath could have been worse. Smiley says a little girl sits outside on a chair outside of her grandfather's business five days a week. Had the explosion occurred on a weekday, the little girl would have been sitting "right where all the windows caved in."
The Department of Water and Power said the blast was caused by faulty equipment in the vault. Officials also said the problem has been isolated and should not affect customers.
No outages were reported to DWP. No injuries were reported.