EMERYVILLE (CBS SF) — A massive fire erupted at a construction site early Wednesday and then spread to a nearby townhouse complex before it was finally contained, authorities said.

The 2:45 a.m. fire quickly built into a 6-alarm blaze as flames roared through the wooden framing of the 5-story apartment complex under construction to rehabilitate the historic Maz Building with 105 apartments and 25,000 square feet of commercial space.

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The fire spread, causing extensive damage to nearby town homes and an auto shop.

The 25 fire units — about 100 firefighters — from Oakland and other nearby communities on scene to battle the blaze were forced to take a defensive stance because the building began to partially collapse.

“When firefighters arrived multiple floors were on fire so they were forced to go into a defensive operation,” Alameda County Fire Chief David Rocha said.

Rocha said the fire grew so quickly “because there was a lot of open framing…fires spread quickly in buildings under construction.”

The demand for water to battle the fire forced East Bay Municipal Utility District officials to increased water pressure at the scene to help firefighters with the defensive attack.

A massive crane onsite was also a source of concern because of fears its foundation had been weakened by exposure to the intense heat from the fire.

50 residents were evacuated from a neighboring complex of townhouses as a precaution as the heat and sparks from the blaze ignited a fire in one of those structures. Rocha said the fire also spread to a neighboring auto body shop.

Alexandra Grant was one of people evacuated who woke up to an inferno outside of her windows.

“This isn’t something you prepare for,” said Grant. “All you saw was flames from the building taking over. You could actually feel the heat inside of our house.”

“The explosions just started going off, one after another,” 39th Street resident Veronica Young said. “It was stronger than fireworks.”

The lights were out along 39th Street when people knocked on the doors of their neighbors to warn them of the fire. Charred remains of the building were strewn on the sidewalk for two or more blocks from the center of the fire.

 

“People were banging on doors screaming ‘Fire! Fire!'” Young said. “Very scary. We thought we were all going to have to leave.”

At least four townhouse units next to the building were damaged and about 50 cars at James Auto Body were destroyed.

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The vehicles are all James Lau’s customers’ cars. He’s hoping insurance will cover them.

“I have no idea,” said Lau. “But my next thing, probably go tell my agent and let him know and go from there.”

Photos: Dramatic Photos Of 6-Alarm Emeryville Fire

The 6-alarm blaze slowed the early morning commute on highways 580, 24 and 980 by drivers slowing to view the massive flames.

As of 6:55 a.m., Alameda County firefighters tweeted that the building is a “total loss.”

Construction workers showed up Wednesday morning to the smoldering remains of the massive blaze.

“It’s really devastating for all of us,” said electrician Andy Haro. “Wow, what are we going to do from here? What’s going to happen?

For now, their jobs are on hold.

There were no injuries and a source of the blaze had yet to be determined. The fire was contained around 8 a.m., but crews were remaining on scene to extinguish hot spots in the smoldering debris.

“Some of the building are very close to one another, so we want to make sure its not spreading to any of the other buildings,” said Rocha. “Once we get the fire completely out our investigators will go into and tried to determine a cause.”

Fire crews used a drone from the Alameda County Sheriff’s Office to provide command staff with an aerial view of the fire and to find those hot spots.

Its infrared camera shows one giant hot spot in what used to be the building’s foundation.

About 50 people were displaced and are being assisted by the American Red Cross at the Emeryville Senior Center at 4321 Salem St., according to Call.

A monetary estimate of the damage the fire caused has not been determined.

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Construction workers told CBS San Francisco someone had broken into the main office of this building over the weekend. They also said that the sprinkler system was installed and working. That will all be part of the fire investigation.