DANBURY — A stretch of Interstate 84 east was closed for more than four hours Tuesday morning because of an overturned tractor-trailer with a possible hazardous material leak, according to officials.

The state Department of Transportation reported the crash between exits 3 and 4 shortly after 6 a.m. Mayor Mark Boughton said later Tuesday morning that the rollover involved a FedEx truck.

While initially only the right lane of travel was closed, by 6:30 a.m., the highway was shut down between the exits as crews worked to clear the crash site.

There was no immediate word on any possible injuries, but initial dispatch reports did not indicate serious injuries.

Shortly after 6:30 a.m., the fire department said the rollover involved a “potential hazardous materials leak” and said crews were in the process of “identifying and stopping the leak.” Fire officials said drivers could expect “extensive delays” through the area.

Shortly after 10 a.m., the Connecticut State Police said the highway’s eastbound lanes had reopened for travel.

This is a developing story. Check back for updates.