(CNN) -- San Francisco firefighters are battling a four-alarm warehouse fire Saturday on Pier 45, the city's fire department says.
A quarter of the pier at Fisherman's Wharf "has been lost to the flames," according to the San Francisco Fire Department PIO.
No injuries have been reported. The pier has been fully evacuated, the department says.
Flames could be seen in the early morning darkness in photos tweeted by Dan Whaley.
The blaze fire was first reported at 4:17 a.m. local time (1:17 a.m. ET) and has been contained to a section of the pier.
The Fire Department tweeted a link to live updates.
Officers report the fire caused a partial building collapse on the southern part of the pier, spread to two buildings on the pier and is in danger of spreading to a third, the Fire Department says.
There is no word yet of a cause.