SAN FRANCISCO (CBS SF) — About a dozen fire personnel responded to an underground transformer explosion near San Francisco’s Pier 3 that blew two manhole covers off Sunday morning, a fire dispatcher said.

The San Francisco Fire Department sent carbon dioxide specialists along with firefighters and paramedics to the blown electrical transformer on the Embarcadero near Pier 3 minutes after a 8:27 a.m. call, a dispatcher said.

No one was injured, but part of the road on the Embarcadero near Pier 3 was closed to traffic.

Transformers, which reduce high energy to lower levels, blow often, but this one is underground instead of on a power line or above ground, the dispatcher said.

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