Tenderloin apartment fires: How light wells have become an unknown, persistent danger 

In mid-July, a two-alarm fire scaled a six-story apartment building in the Tenderloin, burning the inside of the apartment’s light well, a hollow area in the middle of the building that lets light into bathrooms and kitchens. 

The fire didn’t displace any residents, but sent three to the hospital for smoke inhalation. 

It wasn’t the first time San Francisco firefighters stepped onto a scene that started the exact same way. 

Sometimes, it’s much worse. 

On May 13, another fire sparked in the light well of a Tenderloin affordable-housing complex on Turk Street, immediately displacing more than 40 adults, children and animals. As of late July, 14 adults and three minors are still displaced, and 10 units were deemed uninhabitable due to smoke and fire damage. 

“We’ve had so many fires, just this year alone, that have affected over 100 families,” said Bilal Mahmood, San Francisco’s District 5 supervisor, who oversees the Tenderloin and surrounding neighborhoods.

In 2025 and the start of 2026, more fires started in Tenderloin buildings than in any other neighborhood in the city, city data shows. In 2025, in-building fires in the Tenderloin were more than a quarter of the city’s total structure fires. Early data shows that trend is continuing in 2026. 

A significant number of fires last year were noted to have started when “hot embers,” including cigarette butts, met discarded materials like trash, paper and fabric, according to the Fire Department via DataSF. Nearly 20, in fact, started this way. 

Those two things together are a recipe for disaster, said San Francisco Captain Mariano Elias, who was on site for the May and July Tenderloin fires. He said fires started this way — specifically in light wells of buildings — are frequent in that part of the city. 

“It’s human error. I’s the trash (and) throwing discarded cigarette butts,” he said. “Unfortunately, the Tenderloin has been busiest over the years for that exact reason.”

These types of fires not only make the extinguishing process difficult, but they tack on months of work from the city’s fire investigators to determine whether units are safe and habitable after the fire. 

“After the fire is eventually extinguished, firefighters must then remove the charred debris from the light well,” said Ken Cofflin, a retired San Francisco fire fighter and fire inspector for over 25 years. He also noted a long-time concern for fires of this nature in the Tenderloin.

“(The light well) is brick on the exterior, but the inside will be lined with metal,” Elias said. “Obviously, you don’t see that in your own home, but we have to break open the walls to see whether fire has gotten into the units.”

“Its a very big demo job,” Elias continued. “A lot of people’s units get thrashed.”

At 580 Turk St., which caught fire in May, 10 units are still being investigated for fire damage, leaving more than a dozen residents displaced. 

In early August, all 30 households on Turk were moved off the site and into a hotel for a week for general repairs. But the households in the 10 units with significant fire damage will not be able to immediately return. 

Representatives with the San Francisco Community Land Trust, which owns the building, confirmed that the May fire started when a cigarette butt was thrown into the light well. 

“We’ve always known it’s something we have to pay attention to,” said Sarah Scruggs, a program director with the land trust organization. She noted struggles with keeping one of the building’s light wells clean, because it is shared with an adjacent property.

“(Education) is going to be a long term thing we will keep working with tenants on, not to throw trash in the light well.” 

Another director called the ongoing situation a “lesson learned” and stressed that their current top priority is rehousing residents.

How residents can advocate for clean light wells

Hayle Meyerhoff, a lead organizer with the Housing Rights Committee, which helps tenants form unions to fight for better housing conditions, said, “There is broadspread neglect in these buildings,” and noted ongoing issues with light wells. 

In February 2025, a fire started at 907 Valencia St. when a cigarette was flicked into an unkempt light well. One devastating blaze turned into dozens of Mission residents being removed from their homes.

It also sparked a fight with the corporate landlords, Mosser Companies, who told all of the tenants in the rent-controlled building that they would have to move out while the building underwent repairs. 

Corporate landlords in situations like these can benefit from the displacement of vulnerable tenants, Meyerhoff said. In this case, the tenants organized and went on a rent strike that is still ongoing.

To keep buildings safe, Meyerhoff emphasized the rights of every tenant to demand their landlord keep light wells clean and maintain other fire-safety measures in their apartment buildings.

If tenants experience pushback or do not see any significant change in response to their requests, they can file a complaint with the city’s Department of Building Inspection, who will issue a notice of violation with the landlord, forcing them to make improvements.