A high-rise tower under construction in San Francisco, whose upper floors collapsed in a major fire Tuesday, was in danger of collapsing further, and a nearby apartment building remained evacuated, a fire official said on Wednesday.  The fire, which barreled through the apartment’s construction site, sent up black smoke that could be seen for miles around the San Francisco Bay, and continued to burn into Wednesday morning as authorities worked determine what sparked the destructive blaze.  The tower that burned in the two-building, partly built complex had previously stood eight or nine stories tall and was reduced to four stories in the fire, Mindy Talmadge, a spokeswoman for the fire department said. “The good thing is that it collapsed in on itself” instead of toward the street, she said.  The exact cause of the fire – one of the city’s largest in recent years – was under investigation, but crews were welding at the site of the blaze, San Francisco mayor Ed Lee said. The five-alarm fire appears to have started above ground, according to Lee. Crews prevented flames from spreading to nearby buildings.  Talmadge added that 30 apartments in a building across the street had to be evacuated, after heat from the fire blew out that structure’s windows and smoke set off its sprinkler system. Authorities have set up a perimeter around the burned high-rise tower because of the risk of further collapse, and the structure is a total loss, she said.  The fast-moving blaze, which sent an enormous plume of black smoke into the sky, began around 5pm, Tuesday, in San Francisco’s Mission Bay neighborhood, a one-time industrial area that lies along the San Francisco Bay and is home to a University of California, San Francisco campus. Crews remained at the scene on Wednesday morning putting out hotspots.  Nearby buildings were evacuated as more than 150 firefighters battled the flames, using about 90 fire trucks, the San Francisco Chronicle reported. The Chronicle also reported that the project was estimated to cost $227m. Residents of Strata remained evacuated on Wednesday morning.  The San Francisco fire deputy chief of operations, Mark Gonzales, said exterior sprinklers on the building that went off have to be replaced and the fire protection system restored before residents will be allowed back in.  The fire also affected a nearby UCSF research building, where an ember was quickly put out after flying onto the roof, officials said. “I think we’re very lucky that the fire didn’t jump anymore,” Lee said.  The burning building was part of a residential development project with 172 units, according to BRE Properties, the building’s owner. Fire-suppression systems had not yet been installed in the building, making the battle more difficult, fire officials said.  One of the six-story structure’s walls collapsed about an hour after the fire began, and the rest of the building was not expected to remain standing, officials said.  Most of the construction workers at the site finished work for the day around 4pm, but several were still at the site when firefighters arrived, fire officials said.  One firefighter suffered first and second-degree burns to the face and hands, but was treated and released. Another had a minor ankle injury. The site is several blocks from AT&T Park stadium.
Firefighters contain blaze from spreading beyond construction site where it began, as authorities work to determine its cause