Police say the unusual cloud stems from a test of fire-suppression foam from a company near San Jose Mineta International Airport that went wrong.
Firefighters say the foam spread after a fire alarm malfunctioned in a hangar at San Jose airport, causing foam to spew out of the hangar's vents.
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Television news footage late Friday afternoon showed little of the foam that had been several feet deep in spots and had taken up a city block earlier in the day. The cleanup company will distribute a dissolving agent that will break down the bubbles and drive a giant vacuum cleaner truck in the area, Matlow said.
"It was an accidental discharge of the system", Matlow told NBC. I couldnt see anything, said the man (quoted by Newsweek).
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The weird incident was sparked by a malfunctioning fire suppressant system, the Santa Clara Fire Department said on Twitter.
The massive white blob first filled the hangar and then overtook the street, swallowed up vehicles and caused traffic.
Wind also kicked up chunks of foam and blew it like snow.
Anyone who makes contact with the foam should rinse themselves in water and seek medical attention, according to Matlow. While the fluffy white piles may look a lot like Christmas, the chemicals in the foam can be an irritant.