SAN FRANCISCO (KGO) -- Crews controlled a large 4-alarm fire at a building under construction in San Francisco on Tuesday.
The fire happened just before 6 a.m. at Octavia Blvd. and Oak St. in Hayes Valley, displacing several residents.
ABC7 News has learned that concerns about fires in the same area were raised months ago.
The president of the Hayes Valley Neighborhood Association wrote a letter to several city leaders about a series of recent dangerous fires. They started near tent encampments. But, it's not clear if any action was taken.
"There was a car lit on fire close by, there was a tent across the street in the median that was set on fire, and cyclist passing by pulled that person out. We've had encampment fires down the road and those are just the ones this year," said Jennifer Laska, who is president of the Hayes Valley Neighborhood Association.
VIDEO: SF construction site goes up in flames, displacing several neighbors
ABC7 has learned that two months ago, Hayes Valley Neighborhood Association President Jennifer Laska wrote a letter to city officials over "a series of dangerous fires along Octavia Boulevard that started around tent encampments."
In response, Supervisor Dean Preston's office wrote, "We share the concern regarding fires on Octavia and promptly elevated this with city departments."
Late Tuesday, the Mayor's office sent ABC7 News this statement:
"We are aware of past incidents that were found to be related to encampments. The city understands residents in the area are frustrated... However, today's incident is actively under investigation with SFFD, and it is premature to speculate the cause of this incident."
While investigation remains ongoing, some living nearby say it's not fair to blame the unhoused so soon.
"I walk this dog here quite often, I didn't seen no tents on the sidewalk. When they first built this it went up quite fast but the last month or two, dead silence and nothing was up," said Jermaine Delrosario of San Francisco.
VIDEO: SFFD officials update on 4-alarm fire that destroyed building under construction
ABC7 News insider Phil Matier commented on this fire situation saying it's not surprising that this is already turning into a heated argument.
"When you have something like a major fire and questions about how it started plus a history of fires in the neighborhood related to homeless camps - you're going to have people pointing that finger rightly or wrongly, emotionally that's where they go," said Matier.
Tuesday morning video showed scaffolding collapsing with the building fully engulfed in flames.
According to city planning records, the fire happened at a construction site for an apartment building was set to have retail space on the ground level.
"When I pulled up, I thought we were going to see possibly a full block go down," Chief Jeanine Nicholson of the San Francisco Fire Department said.
Chief Nicholson says it wasn't long before this fire grew into a 4-alarm fire, bringing in around 140 firefighters and more than 40 fire trucks.
VIDEO: Fire concerns on fully-engulfed SF construction site raised months ago
After tapping into their auxiliary water system just for the sheer volume of water needed, she says they were able to knock down the flames in under an hour.
"When a building is under construction like this, it was completely wide open, so it's basically a pile of match sticks and there's no sprinkler system in place, there's no sheet rock in place, there's no fire protection anything in place so it's just like Burning Man just setting it off," she said.
Jonathan Baxter, Public Information Officer for SFFD, said the fire spread to four adjoining homes.
Firefighters were able to evacuate everyone from those homes, and no one was injured.
Officials say that six residents will be displaced because of the fire, but that number could increase. The four buildings have fire and water damage, but Baxter says the fire did not spread beyond that.
"We could've lost the entire block," he said as he praised all the crews that responded.
Fire officials are speculating that the heat from the flames was so hot, it's believed to be the culprit behind cracking a number of windows on the apartments across the street on Octavia Street.
"I saw from my apartment the whole commotion, all of the trucks and the firefighters, I was like oh my god, I know it has to be the building right there," Jazmin Mendez, a neighbor said.
Mendez has lived across the street for about four years now. She says she's seen active construction work happening on site up until about a week ago.
But she adds, she wasn't exactly surprised, because this isn't the first time fire officials have responded to this building.
"I've seen the firefighters here before, homeless have been getting inside the building and having fires inside so they've had to put them out before," Mendez said. "Now this entire building, I'm seeing now, is completely gone."
And while the cause of the fire is still under investigation, fire officials are relieved this didn't take out an entire city block.
"They did exactly what they needed to right off the bat, if you don't set a good tone in the first five minutes of the fire, you can lose it," Nicholson said. "Just super proud of what our folks did today."
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