OAKLAND (CBS SF) — A four-alarm fire at a construction site in Oakland Friday morning has forced the evacuation of hundreds people living in neighboring buildings and it remains unclear when they might be allowed to return, according to city officials.

Between 700 and 900 people have been displaced from nearby residences.

The massive four-alarm blaze consumed a large 7-story apartment complex under construction near Oakland’s Lake Merritt, officials said.

Oakland Interim Fire Chief Darin White said his department got a call from a “lone caller” reporting smoke from the project at 4:30 a.m. The fire was well underway by the time firefighters arrived minutes later and was spreading quickly.

“The first units arriving saw heavy smoke billowing from the center of the structure and the fire was rapidly extending,” he said. “Units summoned additional alarms.”

The fire broke out in the area of Grand Avenue and Valdez Street and quickly grew to four alarms as the blaze fueled by building construction materials spread quickly.

In all 80 firefighters battled the blaze and contained the fire around 7:24 a.m. No injuries were reported.

White would not comment on reports that motion sensors located within the project detected some activity before the fire. He said there were security guards at the project.

The fire remained under investigation and local and federal arson teams were on scene. It is the fourth major construction project fire in Oakland in the last year.

“We are going to be relentless in investigating this fire,” said Oakland Mayor Libby Schaaf.

The firefighters were forced to immediately take a defensive position as there was a partial collapse of the building on 24th and Valdez and a large crane was spinning out of control.

Large structure fire in Oakland at 2424 Valdez St in Oakland. Police say it's apartments under construction. Stay with @CBSSF for the latest pic.twitter.com/xExd4kV4cc — Katie Nielsen (@KNielsenKPIX) July 7, 2017

Residents near the burning structure were being told to leave their homes, including a 22-story building, and gathered on the street to watch firefighters battle flames. At least 700 residents had been evacuated from nearby buildings and about 100 ended up at the Cathedral of Christ the Light on Harrison Street and Grand Avenue.

Kamilah Mims lives in an apartment building on Waverly Street next to the parking garage of the building that caught fire. She was standing on Grand Avenue with her kitten Kango and watching firefighters battle the blaze.

“We were sleeping around 5 a.m. when we heard a woman screaming there was a fire across the street,” she said.

Mims said she grabbed her kitten and evacuated her building.

“We were scared, because we weren’t sure if it would spread or what would happen if the building came down,” she said. “I’m happy it didn’t spread.”

Sarah Tyack lives in the building at 100 Grand Ave. just across the street from where the fire broke out. She said she was in her apartment when she heard someone announce there was a fire.

“At first I thought it was our building,” she said.

She said she looked out her window, saw flames and evacuated.

Fire crews monitored the roof tops of nearby buildings to make sure the airborne embers do not ignite other blazes. Alameda County sent additional units to the scene to help Oakland firefighters monitor the local neighborhoods.

Small explosions were heard as the flames moved through the structure and a large crane dangled over the blaze, threatening to possibly collapse. The crane was whirling out of control through the flames, elevating the concerns of firefighters.

Firefighters attacked the blaze using a ‘surround and drown’ tactic. Basically, they have taken a defense approach and were pouring hundreds of gallons of water on the blaze.

The project — the Alta Waverly — was under construction as a mixed used building and was nearing completion in early 2018. It stretches across three blocks and had a planned 225 apartments and 2,300 square feet of retail space. The building also included an underground parking garage.

A huge plume of smoke and ash fell over the neighborhood near the blaze. The fire was visible in San Francisco and to commuters on local freeways in the Oakland area.

Both Gibson McElhaney and Schaaf lamented the loss of the apartment stock, noting that the entire region is in the midst of a housing crisis that has driven rents to stratospheric levels in recent years.

Additionally, the possibility that the fire might have been intentionally set prompted Schaaf to say the city will bring all available resources to bear in order to determine the cause of the fire and to protect the city’s development projects.

Arson investigators from Alameda County, the Oakland Fire Department and the federal Bureau of Alcohol, Tobacco, Firearms and Explosives are on the scene of Friday’s conflagration, and while White stopped short of calling the fire suspicious, he is asking anyone who might have seen anything suspicious to contact the fire department.

Anyone with information is asked to call investigators at (510) 777-3333.

On our way to what's now a 4-alarm fire in #Oakland. Look at all that smoke!! This is from the Bay Bridge. #oaklandfire @CBSSF pic.twitter.com/hYp9dopsur — Jackie Ward (@jackie_ward) July 7, 2017

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