Answer based on context:

Coming off their big home win over San Francisco, the Steelers traveled to St. Louis to take on the Rams in the Edward Jones Dome. After a long delay before the game due to the field catching fire from a pyrotechnical error during the Rams' entrance, the game got underway. Pittsburgh got on the board early with a Josh Scobee field goal, and held the Rams scoreless for the first quarter. Early in the second quarter, Rams' kicker Greg Zuerlein gave them a field goal, tying the game. But, the returning Le'Veon Bell scored on a one-yard run in the second quarter; Pittsburgh failed to convert on a two-point play, but lead 9-3. The score remained this way for most of the game, and neither team scored in the third quarter. Quarterback Ben Roethlisberger injured his left knee mid-third quarter; he was carted off-field and Michael Vick replaced him for the remainder of the game. Zuerlein added to the Rams' score with another field goal, inching the Rams closer 9-6. But, Scobee kicked another field goal for the Steelers, increasing their lead 12-6. St. Louis failed to convert late in the game, and Vick kneeled down to end the game. With their win and a Cleveland loss to Oakland, the Steelers improved to 2-1 and took sole possession of second in the AFC North.

What delayed the game
fire