The holiday weekend kicked off with a four-alarm fire at a fish processing facility on Pier 45 near Fisherman's Wharf. While now under control, the fire spread to the pier below the building and at one point threatened the SS Jeremiah O'Brien, the rare historic WWII ship that survived the storming of Normandy in 1944.

As KPIX reports, the fire broke out around 4:15 a.m. Saturday and fire crews responded to the waterfront between Jones and Taylor Streets. The facility on fire belonged to Caito Fisheries, and reportedly handled processing for much of the Northern California crab fleet.

The warehouse structure reportedly began collapsing as crews arrived. San Francisco’s Fireboat 3 then arrived to battle the blaze from the water, and to save the historic ship — one of only two surviving Liberty ships from the WWII era and a living museum.

“When firefighters arrived, the flames were literally lapping over the Jeremiah O’Brien,” said SFFD spokesman Jonathan Baxter to KPIX. “They literally saved the O’Brien.”

As of 6:15 a.m., as Bay City News reports, crews were still putting out the fire at the warehouse, and plumes of smoke were visible across the Bay and downtown SF as the sun rose Saturday.

No injuries were reported and the cause of the blaze is now under investigation.

Photo: Dan Whaley/Twitter