Tracy warehouse fire still burning as health officials warn smoke may contain toxic gases

A massive fire that destroyed a Medline medical supply warehouse in Tracy was still burning Friday, as health officials warned residents downwind to avoid smoke that may contain toxic gases, carcinogens and other harmful substances.

The fire, reported about 1 p.m. Thursday at 5701 Promontory Parkway, spread rapidly through the roughly 1 million-square-foot facility after firefighters encountered problems with the building's private fire water system, according to the city of Tracy.

Fire officials said the blaze could take days to extinguish.

No Medline employees or on-site personnel were reported missing, the company said. Fire officials said no injuries had been reported, though crews from across the region remained at the scene Friday.

"This is such a unique fire," Tracy Fire Department Chief Randall Bradley said Thursday evening. "A million-square-foot fire is an extremely rare fire in the United States."

The fire began on or near the roof of the warehouse and quickly moved into the building. Bradley said Thursday that "the whole building was engulfed" within about 20 minutes, a rapid spread he attributed in part to high winds, low humidity, heat and the lack of pressurized water at the facility during the initial firefight.

"We don't know why those fire hydrants weren't pressurized," Bradley said, adding that the facility's fire pumps and alarm systems were last tested in January.

The city said the water problem involved the building's private fire protection system. Municipal water pressure remained stable and continued to support firefighting efforts.

Neither of the facility's sprinkler systems appeared to have activated, Bradley said. The cause of the fire and the apparent failure of the fire suppression systems remained under investigation Friday.

The blaze sent a towering column of black smoke over the Tri-Valley and East Bay hills Thursday afternoon. Closer to the fire, county health officials urged residents to stay indoors, close windows and doors, run air conditioning in recirculation mode if available and avoid strenuous outdoor activity.

San Joaquin County Public Health Officer Dr. Maggie Park said smoke from the fire could pose risks, particularly for children, older adults, pregnant people and those with asthma, heart disease or other respiratory conditions.

"Among the chemicals that were consumed in the Medline fire were an assortment of respiratory irritants, toxic gases, carcinogens, and at least one neurotoxin," Park said in a statement.

Park said anyone near the smoke plume who developed sudden respiratory problems, headaches, dizziness, nausea or throat irritation should seek emergency medical evaluation.

The San Joaquin Valley Air Pollution Control District also warned that smoke from the fire could elevate fine-particle pollution in nearby and surrounding communities, depending on wind and weather. Residents were advised to monitor conditions through AirNow.gov.

Medline reported last year that the Tracy facility stored bleach, isopropyl alcohol, lye, sulfuric acid and xylene, according to California Environmental Protection Agency records reviewed by the Chronicle. Xylene is a solvent used in some laboratory and medical processes and can be harmful when inhaled.

Fire officials were also reviewing inventory lists for hazardous materials. Tracy fire officials said several hundred lithium-battery-powered warehouse robots were inside the facility.

The fire's impact extended beyond the Medline property. Wind-driven embers traveled south, igniting several spot fires in the area. Firefighters battled fires involving pallet storage areas and several trailers near a FedEx facility. The exterior of the FedEx building caught fire, but crews were able to prevent the flames from engulfing the main facility, authorities said.

FedEx said Thursday evening that all employees at its Tracy hub were safe and accounted for.

Additional spot fires broke out near Schulte Road and Larch Road and near Tracy Municipal Airport. The city said mutual aid crews contained those fires and prevented further spread.

More than 120 firefighters and dozens of pieces of apparatus responded, including crews from San Joaquin County, Alameda County and neighboring jurisdictions. Incident management personnel from Stanislaus County also supported the response.

Medline, based in Illinois, describes itself as a major medical-surgical supply company serving hospitals, health systems and other care providers. The company said it was working with local authorities and first responders to assess the fire's impact.

"All Medline employees and on-site personnel are accounted for," a Medline spokesperson said. "We are coordinating closely with local authorities and first responders as we assess the fire's impact and will share more details as they become available."

The fire also raised questions about possible disruptions to medical supply chains. Medline's distribution network serves health care providers across the country, and fire officials said crews were working with the company on plans to move undamaged supplies from trailers that had not burned.

Sutter Health said it was monitoring the situation but did not expect broad impacts.

"Our supply chain teams have contingency plans in place to maintain access to critical supplies," the health system said in a statement.

Larissa Gomez, a shift supervisor at a nearby Starbucks, said Thursday that workers from nearby facilities walked toward businesses and a rest stop near Interstate 580 after police blocked roads and some employees could not reach their cars.

"There are probably a dozen people - honestly, more than that - sitting in the shade," Gomez said. "I saw a lot of factory workers and FedEx workers walking this way because they weren't able to reach their cars."

The immediate danger to nearby homes appeared limited. Tracy's mayor said the fire was burning in the city's largest industrial zone, away from residential neighborhoods.

Still, officials said the fire scene remained active Friday, with smoke, hot spots and hazardous-materials concerns likely to keep crews there for days.

"Although we had a very significant fire, the fact that no firefighters were injured and all employees evacuated quickly is astounding," Bradley said.

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This story was originally published June 12, 2026 at 2:07 AM.