Hawkeyed Emergency Scanner listener and unintentionally humorous tweeter @Emergency_in_SF is reporting that the roof of Pier 29 on the city's northern waterfront is on fire. ABC7 confirms the structure fire, which has just been upgraded to 2-alarms.

We'll update as we know more.

The cavalry has arrived: California Beat reports the SFFD have brought in the fire boat Phoenix, which hasn't seen much use lately, to help douse the flames that are now engulfing two stories of the waterfront warehouse. Pier 29 was scheduled to be a main hub for events during the upcoming America's Cup as well.

ABC7 has live video from the air.

Update 2:20 p.m.: A third alarm has been called, meaning there are over 100 firefighters on the scene. Also, F-Line trains aren't running along the Embarcadero and are turning around at the Ferry Building. Shuttle bus service is in place and Muni recommends riders take the cable cars or the 30/45 bus lines to get to Fisherman's Wharf.

2:30 p.m.: California Beat reports that the firefighters are evacuating the warehouse as the fire has engulfed the Embarcadero portal of the pier.

2:45 p.m.: A fourth alarm has been called for the first that has been burning for over an hour now. Most of the roof of the pier has collapsed. According to ABC7's live feed, there are no injuries reported yet, but the smoke may be especially toxic due to the oil-based coating used to waterproof the wood.

As of about 3 p.m., SFFD reports that the fire is under control. The official line from the America's Cup people confirms Pier 29 is part of the America's Cup village, but it was not under construction when the fire broke out this afternoon.

And look: there's a rainbow!