Residents of the California town of Santa Clara had a surreal experience on Friday (18 November) when parts of the town were submerged by up to 10 feet (3 metres) of a mysterious white foam. Locals in the town, 45 miles (72 km) south of San Francisco, could have been forgiven for thinking they'd been invaded by a giant alien blob.

The mystery was solved when Santa Clara Fire Department discovered the foam was a fire retardant seeping from a hangar at nearby San Jose International Airport. The fire department warned that the retardant, which is used to starve fires of oxygen, is a carcinogen in its strongest form and can cause skin irritation. Locals were advised to steer clear or seek medical attention, but most residents didn't seem too concerned, playing in the foam and even cycling through it.

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"Yeah, someone had to do it," one cyclist who took the plunge told a local Fox News affiliate. "We were on the other side and the officers over there were like 'you should ride through.' And I was like, 'OK you guys don't mind?' So we decided to do it."

Another cyclist told reporters the only real danger was bumping into street signs. "It just feels like soap, it smells like it too. I couldn't see anything," said the man (quoted by Newsweek). "In the middle it's probably 10ft tall. I tried to stand up in the middle to see where I was going but I couldn't get out of it."

Santa Clara foam blob California
Parts of Santa Clara were submerged beneath up to 10 feet of foam REUTERS/Elijah Nouvelage

San Jose fire Capt. Mitch Matlow told The Mercury News the discharge began when a fire alarm went off by accident. "The purpose is to prevent a flammable liquid fire inside the hangar from spreading," said Matlow. "If there had been a fire, this system would've worked very well."

However the fun was short-lived, as the fire department tweeted that a clean-up operation was underway and all would soon be back to normal. In the meantime, drivers were advised to avoid the area.

California