San Jose fire department warned people to not touch the foam, as it can cause skin irritation.
Firefighters are on the scene.
The foam has flooded the hangar at San Jose airport and is blowing into surrounding surface streets. Fire officials say foam was released after a fire alarm malfunctioned at the hangar, which deals with jet planes.
The hangar is owned by Signature Flight Support and accommodates large cabin sized aircraft. They provide support services like aviation fueling.