Interstate 84 East was closed at exit 4 in Danbury after a tractor-trailer overturned between exits 3 and 4 around 6 a.m.
The highway has reopened and the right lane remains closed as of 1 p.m.
The fire department posted that there might have been a hazardous materials leak and crews were in the process of identifying and stopping the leak.
No additional information was immediately available.
