Live updates: Officials call Tracy warehouse fire 1 of largest in US; could burn for days

At a press conference Friday evening, Tracy officials said the density and volume of the smoke in the area have changed drastically since the fire first broke out at the Medline distribution center Thursday afternoon.

At a press conference Friday evening, Tracy officials said the density and volume of the smoke in the area have changed drastically since the fire first broke out at the Medline distribution center Thursday afternoon.

The color of the smoke is lighter than the original black plumes from the day before and even the darker shades from hours earlier, according to Deputy Chief Brian Bagely with Tracy Fire. Bagely also noted that the smoke was not traveling as far in the later hours, noting that favorable wind directions were keeping the fire away from nearby homes.

Fire crews are said to be using water to extinguish the flames at about 4,000 gallons per minute, with the excess water being captured by local bio-swales and other capture structures. Environmental specialists are expected to conduct water sampling to detect any toxins in storm drains.

Mayor Dan Arriola said the city is planning to conduct street sweeping to address debris from the fire. Residents are urged not to touch any debris they see.

The city is also working closely with local agencies to monitor the air quality. Arriola noted that "portions of the city have moderate areas of concerns for air quality."

Residents can get the latest air quality information here.

Watch the full update in the player above.

Firefighters described the Medline distribution warehouse fire as one of the worst fires of its kind during a press conference Monday as smoke continued to billow Friday morning.

Firefighters described the Medline distribution warehouse fire as one of the worst fires of its kind as smoke continued to billow Friday morning.

It's one of the largest warehouse fires in the U.S. with 900 people who are employed there but only 120 workers there.

"There's been distribution centers that have burned throughout our nation, but to have one, you know, over a million square feet, there's only been two or three that we are aware of, and so it's very, very challenging, you know, you can imagine it's a skyscraper laying on its side," said Brian Bagley, deputy chief with the Tracy Fire Department.

The cause of the fire remains under investigation. Officials said it started inside the facility, near the top of the roof. When crews arrived, they reported that fire sprinklers had not activated and that yard hydrants on site were not working. Firefighters instead connected to a municipal hydrant located off-site.

"It took two fire engines just to connect from the fire hydrant to get it close enough to apply water to the actual fire," Bagley said.

The adjacent FedEx facility almost caught fire, as officials say they quickly went into containment mode. There were several grass fires and 200 pallets against the FedEx facility caught fire, that were mitigated with the help of mutual aid.

The trailers mostly full of medical commodities adjacent to the building were also a challenge for firefighters overnight.

Fire officials said the building's sprinkler system was last inspected in January and was functioning at that time. Investigators are now working to determine why it failed during the fire.

Authorities also raised concerns about hazardous materials inside the warehouse. While a full inventory has not been released, officials said the building contained robots equipped with lithium-ion batteries.

"That all burned, and lithium ion batteries that, you know, get destroyed by fire end up causing, you know, hydrogen fluoride gas, and that's not good," Bagley said.

The Medline distribution center supplies medical goods across Northern California. Fire officials said they are working with the company to move trucks carrying unaffected supplies out of the area and on to their destinations as crews continue battling the fire.

Medline and FedEx have released statements Monday morning as a massive fire continues to burn at the Medline distribution facility. FedEx confirmed that its adjacent building was not damaged.

Here is Medline's statement:

"On June 11, a fire impacted Medline's distribution facility in Tracy, California. We are grateful that all Medline employees and on-site personnel were safely evacuated and accounted for.

The Tracy facility is part of Medline's expansive distribution network, and specifically a local distribution center largely serving parts of Northern California.

Medline's supply chain is designed with resiliency, scale and flexibility at its core. Immediately following this incident, Medline activated a command center and a network contingency plan and began incorporating secondary and tertiary distribution centers. Product distribution previously supported by the Tracy facility has been reassigned and it is in the process of being deployed to other facilities within our regional network to help maintain service and support customer needs."

Here is FedEx's statement:

"Our thoughts remain with those affected by this event. Safety is our top priority. We are thankful our team members are safe and appreciate the efforts of the local fire department and our safety team. As this remains an active scene, additional questions should be directed to the local authorities. Our building sustained no damages. Once the fire department clears the scene, our team will implement contingency plans to ensure service continuity. Customers with questions about their shipments can track their packages on fedex.com."

A massive warehouse fire that started around 1 p.m. Thursday is still burning Friday morning.

A massive warehouse fire that started around 1 p.m. Thursday is still burning Friday morning.

The million-square-foot warehouse was torched with black smoke billowing into the sky, and officials say it could keep going for days.

As of Friday morning, there is still a large plume of smoke that is being described as a "wall of smoke."

Fire crews are expected to be on scene the next few days.

The Tracy Fire Department says when firefighters first arrived inside the building, the warehouse's sprinkler system was not working.

They also said that the fire hydrants built in the facility weren't providing good pressure.

"We had problems with water pressure initially on the fire," Chief Randall Bradley said. "The fire hydrants within the yard of the facility had lacked pressure. So we had to connect to the fire hydrants on the street from the water, municipal water system."