Update: Massive fire destroys building under construction in San Francisco's Hayes Valley

A massive fire swept through a building under construction in San Francisco's Hayes Valley neighborhood Tuesday morning, causing it to partially collapse.

The San Francisco Fire Department said the fire was reported at 5:54 a.m. in the area of Octavia and Oak Streets and quickly added a second alarm.

UPDATE: Hayes Valley residents repeat calls for action after destructive construction site fire

At 6:16 a.m., the department said on social media the fire had reached three alarms and urged people to avoid the area.

As of 6:30 a.m., the fire had reached four alarms. The department said there were 40 fire apparatuses on the scene along with 130 firefighters.

Five neighboring buildings were damaged by the blaze, and eight people were displaced, said fire department spokesman Capt. Jonathan Baxter. No one was injured. 

There were photos and vide of the fire being posted by residents who lived in the area that showed just how high the flames rose during the height of the blaze.

"When I pulled up, I thought we were going to see possibly a full block go down," said San Francisco Fire Chief Jeanine Nicholson. "So, really proud of the [fire department] members and what they did today, really limiting, limiting the impact to an entire neighborhood."

Nicholson said firefighters were monitoring the scaffolding around what remained of the building, which was unstable and would require dismantling.

"When I pulled up, I thought we were going to see possibly a full block go down," said San Francisco Fire Chief Jeanine Nicholson. "So, really proud of the [fire department] members and what they did today, really limiting, limiting the impact to an entire neighborhood."

Nicholson said firefighters were monitoring the scaffolding around what remained of the building, which was unstable and would require dismantling.

Baxter said the department's fire investigation task force was probing the cause of the blaze. A Contra Costa County Sheriff's K-9 was seen picking through the rubble from the fire.

"This is an accelerant K-9. This K-9 is used by our investigators to help them eliminate or add to their investigation and by no means should be indicative of a specific cause of the fire."

Baxter said a building under construction burns quickly and at a higher intensity because it lacks doors, sprinkler systems and walls that could limit the fire's spread. The heat from the fire damaged some of the fire apparatuses and cracked windows all the way across Octavia Boulevard, which runs parallel to Octavia Street along a several-block stretch. 

"Octavia Street is a six-lane street with an actual island in between that. We are a great distance from the fire building to across the street,' said Baxter. This fire was hot enough to cause cracks in the windows of the building across the street.

Residents were told to expect traffic delays in the area as fire crews remained on the scene.

There was no immediate word on what caused the fire.