San Francisco firefighters responded to a one-alarm fire early Tuesday that appears to have broken out, improbably, underneath and at the edge of Pier 28 in the rain.

Firefighters reponded at 4:05 am to a report of a blaze on Pier 28 — the SFFD reported the fire as being on Pier 30, though videos from the scene appeared to show them extinguishing it on Pier 28, next door.

All lanes of the Embarcadero were temporarily closed in both directions as hose lines were running across the roadway.

The fire appeared to be underneath the wooden structure of the pier, at its far edge in the Bay, and there's been no explanation for its cause — which seems fairly improbable during a rainstorm?

The fire was extinguished and there were no injuries.

All lanes of Embarcadero are back open.