BRIDGEVILLE, Del. — A 39-year-old woman suffered critical injuries Sunday after an apparatus used to launch pumpkins into the air exploded at a large outdoor competition, Delaware State Police said.

A 56-year-old man also was hurt with nonlife threatening injuries. Both had been struck by debris from the explosion.

The incident occurred at the Punkin Chunkin Contest in Bridgeville, which is about 30 miles south of Dover. The competition involves dozens of contestants launching pumpkins from homemade contraptions, many of which are air-powered and hauled on the back of trucks.

Spectator David Aronson, 52, of Falls Church, Va., said he was about 25 yards behind the cannon when it exploded. He said it had just fired a pumpkin when a piece blew off the launcher that was the size of a car door.

“It arcs down on this woman who is running away as it hits her,” he said.