A tanker truck carrying 8,500 gallons of gasoline burst into flames on I-95 south just after Exit 15 in Norwalk, shutting down one of the country's busiest highways on Thursday.

MORE: I-95 in Norwalk closed until at least Monday following tractor-trailer fire

It happened around 5:30 a.m. under the Fairfield Avenue bridge. Officials said no one was hurt.

The massive fire required every Norwalk fire truck to respond, along with some from surrounding towns and cities.

In a news conference Thursday evening, officials said engineers determined it was too dangerous for traffic to pass under the bridge in either direction closing I-95 completely.

Gov. Ned Lamont declared a state of emergency in response to the fire and called on the federal government for help.

“It is an emergency declaration. I filed that with the feds just in the last hour, hoping to get federal reimbursement for the replacement of the bridge,” said Lamont.

Norwalk officials said a new overpass would likely take at least a year to build.

“Demolition is going to start first thing tomorrow morning,” said Lamont.

He said the hope is to reopen the interstate by Monday morning.

Environmental crews worked throughout the day to clean up gasoline and firefighting foam.

“The DEEP Emergency Response and Spill Prevention Division team has conducted air monitoring with handheld technology, and we believe there's no danger, no impact to air quality due to the burned gasoline,” Deputy Commissioner Emma Cimino said. “We also believe there's no impact on the Norwalk River or the harbor.