Firefighters put out a fire Thursday that burned several rows of seats and a box at the Denver Broncos Stadium.

The fire started on the fourth level of Empower Field in Mile High after 2 p.m. and spread to the third level, burning at least six rows of seats in two sections. Firefighters quickly managed to get the fire under control, but they were trying to determine if it had spread to other areas of the football field, which has a capacity of 76,125 people.

In a statement on Twitter, stadium officials said the fire occurred in a construction area near the East Club lobby. At least 100 people were attending an event in the second division, but the stadium was empty.

About 75 firefighters were at the scene at the height of the fire. There were no reports of injuries.

News helicopter footage showed several firefighters using garden hoses to put out the blaze, which sent large plumes of black smoke from the stadium near downtown Denver. The Denver Fire Department tweeted several photos showing the large, spreading flames.

Captain Greg Bexley, a spokesman for the fire department, said the fire appeared to have originated in the inn, but was partially extinguished by the sprinkler system. Then it spreads to the plastic seats.

Investigators have not determined the cause of the fire, which burned at least 1,000 square feet.

A welding torch may have started a similar fire that burned plastic seats in the western stands of the old Mile High Stadium in January 2002.