SAN FRANCISCO—An underground explosion sent a PG&E manhole cover flying into the air on Wednesday, August 31 in downtown San Francisco startling several bystanders amidst the morning commute.

The San Francisco Fire Department received word of the incident at approximately 8:30 a.m. and arrived to the scene shortly after, which was located in San Francisco’s Financial District at 350 Bush St., between Montgomery and Kearny Streets.

When fire officials arrived on the scene, there was a plume of smoke hovering over the manhole, but no visible flames. PG&E crews were called to investigate and arrived on the scene before 9:15 a.m., according to reports.

At 8:29 a.m., the SFFD tweeted, “***AVOID AREA*** 350 BUSH PGE VAULT manhole cover blew off no injuries SFFD ON SCENE/ PGE ENROUTE/ NO FIRE 0828.”

PG&E crews descended into the cavity to survey the damage and concluded that a busted fire hydrant at Belden Place and Bush Street was likely the cause, according to the SFFD.

In the moments leading up to the explosion, a car struck a fire hydrant approximately a half a block away, which sent water streaming downhill and leaking into PG&E underground equipment—causing it to malfunction.

The SFFD and PG&E crews remained in the area most of Wednesday morning until the problem was resolved. They cleared the scene shortly after 10:30 a.m.

There was no imminent threat to the surrounding area and no injuries or power outages were reported, according to the SFFD. Only one lane was closed, so traffic impacts were minimal, but drivers were advised to expect delays and if possible, avoid the area entirely.