UPDATE, March 30 9 p.m.: ATLANTA (AP) —  Atlanta officials say a massive fire that burned for more than an hour and caused the collapse of an interstate overpass has been extinguished.

Fire department spokesman Sgt. Cortez Stafford told the Atlanta Journal-Constitution (http://on-ajc.com/2nl88ef ) that the fire was under control Thursday night. Stafford said a portion of the bridge on I-85 fell about 7 p.m.

Witnesses say troopers told motorists to turn around on the bridge because they were concerned about its integrity. Minutes later, the bridge collapsed.

Capt. Mark Perry of the Georgia State Patrol told the newspaper that the agency doesn't know what started the fire but that terrorism is not suspected.

The Atlanta Police Department issues a traffic alert advising drivers to find alternate routes around the area.

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March 30, 7:50 p.m.: A large fire has caused an overpass on Interstate 85 to collapse in Atlanta.

WSB-TV (http://2wsb.tv/2omVYDp) reports the massive blaze is burning underneath I-85 northbound near Piedmont Road. It has shut down several roads in northeast Atlanta.

Witnesses say troopers were telling cars to turn around on the bridge because they were concerned about its integrity. Minutes later, the bridge collapsed.

Black smoke can be seen for miles.

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Information from: WSB-TV, http://www.wsbtv.com/index.html