Photo by @colerise via Twitter
"Pier 29 fire! Roof collapsing," reads the accompanying message by @colerise via Twitter.
The Mercury News is reporting that firefighters are at the scene of a four-alarm blaze at Pier 29 in San Francisco.
The fire was reported at about 1:50 p.m., and responders are working to extinguish the situation from the outside. No injuries have been reported.
Photos via Twitter show Pier 29, the future site of America's Cup, suffering at least a partial roof collapse in the incident. The site is expected to central to the activities of the 2013 race, and construction has been ongoing at the location.