A mysterious green liquid was found oozing onto a Detroit-area highway on Friday, causing authorities to shut down that portion of Interstate 696 and bringing in federal agencies to investigate the spillage.

Michigan State Police announced Saturday on Twitter that the liquid was the chemical hexavalent chromium, and it had been leaking from the basement of a local business.

Hopefully this will answer some questions we have been getting about I 696 in Madison Heights. At about 2 30 PM on 12/20, we were asked by Madison Heights Fire Dispatch to block the right lane of east bound I-696 near Couzens while the fire department cleaned up a liquid spill. pic.twitter.com/WGFy5sYDkk — MSP Metro Detroit (@mspmetrodet) December 21, 2019

Hexavalent chromium is typically produced during plating processes and is a known carcinogen, according to the Occupational Safety and Health Administration.

The chemical can cause damage to the kidneys, liver, eyes, skin, and respiratory system.

The chemical had been leaking from the local business’s basement into the ground to a drain that emptied out onto the highway. Had it not been discovered, the cancer-causing chemical could have ended up in Lake St. Clair, Macomb County Public Works Commissioner Candace Miller wrote on Facebook Friday.

“The Environmental Protection Agency (EPA) indicated that once the chemical came up thru the drain, it froze into a yellow blob,” police tweeted. “The plan to dispose of the chemical is to bring in a type of excavator, scoop up the frozen waste, and place it into a safe container.”

The Environmental Protection Agency (EPA) indicated that once the chemical came up thru the drain, it froze into a yellow blob. The plan to dispose of the chemical is to bring in a type of excavator, scoop up the frozen waste, and place it into a safe container. — MSP Metro Detroit (@mspmetrodet) December 21, 2019

Officials told WDIV that the cleanup process could take days, and results from testing the substance should be available within a week.

“We have cleaned out the sewers and the clean out drains between the facility and 696,” said Jill Greenberg, a spokeswoman for the Michigan Department of Environment, Great Lakes and Energy. “We’re also in the process of cleaning up the basement of the facility.”

Tricia Edwards, who is with the EPA, said the cleanup would take a while because the substance was mixing with the clay in the area.

Hexavalent chromium, also known as chromium-6, is the chemical that was front-and-center in the 2000 movie Erin Brockovich, which starred Julia Roberts as the activist who sued a California power company over the chemical leaking into the water supply.