An explosion at a southern Indiana wood laminate plant sent eight workers to a hospital with injuries, caused walls to collapse and started a fire, authorities said.

The injuries from the Friday morning explosion were not considered life-threatening, and all eight workers were expected to be released later in the day, said Rita Howell, a spokeswoman for Jasper Memorial Hospital and Health Care Center.

The explosion at the Indiana Laminate plant occurred when a board became stuck inside a machine, caused a spark and triggered the explosion, Fire Chief Kenny Hochgesang said.

"We have several walls that have collapsed," Hochgesang said.

The explosion also caused a fire in a dust-collection system outside the plant, and it was extinguished in 40 minutes, Hochgesang said.

At least six of those hurt were working in the immediate area of the explosion, Hochgesang said. The plant employs about 60 people, but not all were believed to be there at the time.

The explosion occurred about 7:15 a.m. at the plant on the southwest side of Jasper, about 50 miles northeast of Evansville.

Workers built dikes to contain the water runoff to mitigate any environmental threats, Hochgesang said.