An underground explosion rocked the downtown area and sent a manhole cover flying through the air during the busy afternoon exodus from businesses.

The San Francisco Fire Department responded to the explosion at California and Drumm streets at about 4:04 p.m. and shot a fire retardant substance through several manholes. The black smoke billowing from the manholes ceased by about 4:30 p.m.

Witnesses said they could feel and hear the explosion from as far away as the Ferry Building and as high as the 30th floor of Spear Tower across Market Street.

Several people also heard a second clang when a manhole cover in the middle of the intersection of California and Drumm streets hit the asphalt and split into several pieces.

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That manhole cover was directly on top of the cable car line and another manhole billowed smoke next to a crosswalk in front of the Hyatt Regency. A third manhole in front of a Wells Fargo bank also blew smoke into the wind.

Representatives from Pacific Gas & Electric Co. were on the scene within minutes.

PG&E spokeswoman Tamar Sarkissian said Tuesday night that they determined the explosion was caused by cable failure.

She did say that PG&E is working to determine what caused the cable failure and added that 11 customers had been “de-energized” while the company pinpointed and fixed the problem.

Those customers were not expected to have power back until about 6 a.m. today, she said.

No one was injured by the blast.

The blast affected the California cable car line, the 1-California and the 41-Union, according to Muni.

bbegin@sfexaminer.com  

Bay City News contributed to this report.