CASTRO VALLEY, CA — A quiet Sunday afternoon shattered into chaos when a major three-alarm fire erupted in a residential Castro Valley neighborhood, tearing through multiple properties, leaving families homeless, and prompting a massive mutual aid response.

The fast-moving blaze broke out on the afternoon of June 28, 2026, forcing frantic evacuations as heavy plumes of dark gray smoke became visible for miles across the East Bay.

Emergency dispatchers with the Alameda County Fire Department began receiving frantic calls around 3:51 p.m. regarding a residential structure fire in the 22000 block of Queen Street. Neighbors living near Castro Valley Boulevard reported hearing a loud, startling boom moments before thick, black smoke began billowing into the sky.

The fire reportedly originated at a home identified by officials as a hoarding property. Packed with combustible materials, the residence acted as a fuel source, causing the flames to rapidly intensify and spread out of control. Within minutes, the extreme heat and shifting winds pushed the fire to adjacent properties, engulfing two separate homes and an accessory dwelling unit (ADU).

Recognizing the immediate threat to the densely packed residential block, fire commanders quickly escalated the response to a third alarm. The severity of the blaze triggered a widespread mutual aid call, drawing engines, trucks, and specialized equipment from neighboring jurisdictions, including the Oakland, Hayward, and City of Alameda fire departments.

Dozens of firefighters launched an aggressive defensive and offensive attack, deploying high-pressure hose lines to douse the structures while simultaneously drenching nearby roofs to prevent the fire from leaping further down Queen Street. However, ground crews faced challenging hazards due to a heavy volume of materials inside the primary home, which severely restricted their access and created intense, localized hot spots.

During the grueling battle to contain the inferno, one firefighter suffered a minor injury and was treated by emergency medical personnel. No civilian injuries were reported, largely due to the quick actions of neighbors who alerted one another to flee.

While firefighters successfully stopped the perimeter of the fire from expanding further into the neighborhood, the destruction left behind is severe.

In just one of the affected homes, six people, three dogs, and a cat were abruptly displaced after their living spaces were rendered completely uninhabitable. Fire officials are still working to determine the exact number of individuals affected and displaced in the second damaged home.

"It smelled like fireworks, and then suddenly the whole back of the property was just gone," one local resident shared on social media, describing the speed of the disaster.

The American Red Cross was promptly called to the scene to provide emergency housing, food, and emotional support to the dislocated families and their pets. Meanwhile, arson investigators and fire officials remain on-site working to determine the exact mechanical or accidental trigger behind the initial explosion.