SEATTLE - Northbound Interstate 5 near Interstate 90 in Seattle was completely shut down Wednesday afternoon after a semi truck spilled a couple gallons of toxic chemical onto the freeway.
The Seattle Fire Department said a placard on the truck indicated the leaking liquid was a sodium borohydride and sodium hydroxide solution.
"It's a toxic substance, and it can be deadly in large amounts," fire department spokesman Kyle Moore said. "It's something we didn't want people driving over in their cars. We didn't want vapors to get into their air conditioning systems, so as soon as we learned what the substance was, we shut down all lanes of northbound I-5."
Emergency crews said the substance is used to bleach pulp and wood products.
The leak caused crews to closed lanes for four hours and 20 minutes.
At its worst, the backup was about four miles.
Drivers stuck between Spokane Street and the incident near I-90 were turned around to exit at Spokane Street.
Initially, Seattle fire believed the spill was 50 gallons, but later said only two gallons had leaked. Crews spread sand on the spill.