LITTLETON, Mass. (AP) – Commuters driving along Interstate 495 in Littleton on Wednesday morning were seeing red, and it wasn’t just because of the heavy traffic.

About a 500-yard stretch of the northbound lanes turned from black to crimson after a tractor-trailer spilled thousands of gallons of red dye on the highway late Tuesday night.

The entire highway was shut down and traffic diverted onto secondary roads for the cleanup, but the road reopened on Wednesday morning even though it was still red.

The dye, used to stain wood mulch, is non-toxic, state environmental officials said.