An explosion in a sixth-floor unit at 50 Golden Gate Ave. set off the fire alarm and appears to have triggered the Tenderloin blaze that displaced 68 residents last week, according to a surveillance video obtained by Mission Local.
In the video, an audible boom can be heard as a flash of light and large flames burst out of the sixth-floor apartment’s interior bathroom window. A fire alarm begins ringing, and two voices can be heard calling dogs before everyone rushes out of the unit.
Within 30 seconds, thick smoke can be seen filling the hallway.
Multiple residents told Mission Local that they heard the explosion after 3 a.m. on Friday, including a resident who was awoken by the sound five floors below on the first floor.
“I couldn’t really see much of anything,” said one resident who responded to the sixth-floor unit and emptied an entire fire extinguisher to no avail.
Though the video shows the fire originated near the bathroom, the neighbor who ran in with the fire extinguisher said the fire had already spread to the other side of the apartment when they arrived. “Whatever happened spread very, very quickly.”
Just what exploded at 3 a.m. in that sixth-floor unit is still unclear.
Dustin Winn, a battalion chief with the fire department, told dozens of residents who gathered at a town hall meeting on Tuesday evening that the cause of the fire is still under investigation. An attendee offered the video footage to Winn, and it appeared this was the first he was learning of it. He asked the attendee to share it with arson investigators.
Over 100 firefighters fought the fire for hours before dawn on Friday morning, and were able to contain it to the sixth floor, though water damage is expected on lower floors. Despite the lack of sprinklers and the out-of-service elevator, residents were able to evacuate the building and no injuries have been reported. All of the 77-unit building’s residents have been displaced.
Justine Shoemaker, the director of property management for Mosser Companies, which manages the building, told Mission Local that the company intends to assist all residents in finding housing. The company is working to place displaced residents in other buildings with their rent-controlled lease agreements intact.
“You have the absolute right to return to your units upon repair and completion of those repairs, we will not stop you from that. We absolutely want that to happen, yes,” Shoemaker said before a crowd of anxious residents who pressed the company for firm answers on Tuesday. Many fire victims never get to return to their buildings despite having the right to. “We will work and do our very best to find your housing or temporary housing during that time at your current rent.”
For now, Shoemaker said about 20 of the residents were sent to the Motel 6 in the Tenderloin and another 20 were sent to the Mosser Hotel in SoMa. Others chose to find their own accommodations.
Despite reassurances of support from Mosser and the city’s Human Services Agency, many residents of 50 Golden Gate are uncertain where they will be placed when their hotel stay is set to expire on Friday. They are organizing a tenants association with the Housing Rights Committee of San Francisco, fearing eviction or loss of their leases.
Mosser Companies is also aware of the source of the fire.
“We know where the fire started, it’s on video,” said Neveo Mosser, the CEO, in an interview. He said the incident occurred at 3:10 a.m. but declined to comment on it, because of the ongoing investigation.
The building at 50 Golden Gate Ave. on Dec. 12, 2025, the morning a fire displaced 68 people. Photo by Eleni Balakrishnan.
In the meantime, residents have not been permitted to return to their apartments for their belongings, as the building roof collapsed and officials have determined the building to be unsafe for entry until basic repairs have been completed.
Many left their apartments in the middle of the night without essentials like clothing, wallets or phones. Most residents were given $350 Red Cross gift cards to purchase essentials like food and work clothing, but many said that money quickly ran out.
The Motel 6, which a Mosser representative said was for “everybody who needed special accommodations,” turned out to not have heating. Shoemaker said that was a “complete surprise” — and while some residents now have space heaters, others still don’t.
“They told me they didn’t have any more, that they had already distributed the ones they had among other neighbors,” said one resident in Spanish. Her family gave her blankets and towels.
When she goes downstairs to heat up food in the microwave, “it’s horrible because we open the microwave and cockroaches come crawling out,” she said. “I feel fortunate that my family were the ones who donated — my mom, my aunt, my cousins. They helped me.”