For a moment on Friday, it looked like a slice of Santa Clara was covered in snow, and just in time for the holiday season.
Turns out the bubbling white froth was a sea of foam that spilled onto Martin Avenue and beyond, after a fire suppression system malfunctioned at an airplane hangar at San Jose Mineta International Airport.
The fire alarm at the Signature Flight Services hangar went off just after 11 a.m., according to San Jose Fire Department Chief Mitch Matlow. Soon after waves of foam covered cars and street signs.
The airplane hangar's fire suppression system is designed to fill the building with foam to knock down the fire. There was no fire at the building, Matlow said.
"It was an accidental discharge of the system," he said. "Why the system went off here I don't know. No one can go into the hangar because the foam is 10 feet deep in that building."
As of Friday night, three environmental cleanup contractors worked feverishly to scoop up what began as an avalanche of fire-fighting foam. But with a weekend rain storm approaching, hazmat crews rushed to gather it all before runoff threatened to wash it into the San Francisco Bay.
"The concentrate is carcinogenic, but in its diluted form, it is an irritant," Matlow said. "If you got it in your eyes, it could create a problem."
A spokesman for Signature Flight Services could not recall a similar incident in its facilities before Friday.
Bystanders, however, treated the suds playfully.
"Looks like snow time, Christmas time," Gerardo Medel said.
One bicyclist rode through the snow, er, foam, for fun. Blake Harrington said he kept his "eyes closed the whole time."
And onlookers and camera crews descended on scene.
"I love that part when the wind blows it," Lisa Munoz said. It "looks like waves."
Instantly the jokes poured in with the hashtag "#FoamBlob" trending on Twitter. The San Francisco Chronicle called it "Foamnado," and Dennis Romero turned the mysterby blob into a political joke.
"Relax people," he tweeted. "The #BayAreaBlob is just the Trump nation slowly making America white again."