On Thursday night, a massive fire caused a bridge to collapse on Interstate 85 in Atlanta, which is one of the busiest stretches of roadway in America. This caused rush hour traffic to back up for several miles and creating a long-term “transportation crisis” according to the mayor.

A fire and an ensuing collapse:

At 6:21 p.m. ET, the huge fire was reported underneath the bridge on the northbound side. This is near where the interstate merges with another major artery, State Highway 400, which forced authorities to close the interstate and turn drivers around during the evening rush. Then, at about 7 p.m., the bridge collapsed.

Traffic was successfully turned back by authorities before the bridge collapsed but as state troopers worked on a way to get vehicles off the roadway, thousands of motorists were locked in place on the interstate.

Georgia Gov. Nathan Deal said no injuries were reported and on Thursday night, he declared a state of emergency for Atlanta and Fulton County.

At about 8pm, the fire was under control. But the principal problem was the collapsed bridge. According to the state Transportation Department, all lanes of I-85 in the area are expected to be blocked indefinitely.

Late Thursday, Mayor Kasim Reed held a news conference where he said that it’s as serious a transportation crisis as they could have, adding that FBI agents were on the scene “to work out what happened” but that the agency had reported no suspected link to terrorism.

The situation was described as a “crisis” by Russell McMurry, commissioner of the Georgia Department of Transportation also.

McMurry said at a news conference at 11 p.m. ET, almost five hours after the fire started, that transportation crews still couldn’t get access to the scene because of the heat being generated by the flames.

Other parts of I-85 had been “compromised” according to Atlanta Fire Chief Kelvin Cochran, including the important interchange over Piedmont Road, which leads to the state Capitol.

Cochran thanked state troopers with saving lives by stopping all of the traffic in the 40 minutes before the bridge collapsed.

Deal said in a televised statement that the cause of the fire is still undetermined, but authorities are focusing on the possibility that polyvinyl chloride (PVC) piping commonly used in construction may have ignited for some reason, as large amounts of PVC pipe were stored under the bridge.

The collapse happened near the high end downtown Atlanta district of Buckhead, which is home to some of the city’s biggest businesses, medical centers and diplomatic missions.

An important highway:

On an average weekday, more than 225,000 vehicles traveled through the affected area. Which made state and local officials to plead with Atlantans to do whatever they could to stay away for as long as it takes

Chairman of the Fulton County Board of Commissioners, John Eaves, asked businesses in the area to make flexible work schedules and encourage employees to use public transit.

To accommodate the extra riders, the Metropolitan Atlanta Rapid Transit Authority said it was arranging extended service.

All schools would be closed Friday as per the DeKalb County School System and the Atlanta school system stated it would find alternative bus routes through the area.

Atlanta has he fourth-worst traffic in America and the ninth worst in the world according to Inrix, a global transportation research firm. But the entire Southeast will be impacted by the collapse.

In the eastern half of the country, I-85 is one of the busiest freeways. It carries vehicles almost 700 miles from southern Alabama through Virginia. It’s considered an important commercial throughway for trucks making deliveries to businesses and warehouses in major commercial centers like Montgomery, Alabama, and Charlotte, North Carolina.