- Associated Press - Wednesday, April 23, 2014

DENVER (AP) - Authorities say three people are hurt after an explosion at a marijuana growing operation in Denver.

Investigators say the explosion happened Wednesday while the people were using butane to extract the intoxicating chemical THC from the marijuana plant. Denver Fire spokesman Mark Watson says the injured people were likely trying to make hash oil. The process is dangerous and has caused several similar explosions in Colorado and around the country.

Watson says it does not appear the marijuana growing operation was permitted, and the extraction process is illegal. Two men and a woman were taken to hospitals with second-degree burns.

Watson says the building, in an industrial area, wasn’t damaged. Police haven’t made any arrests.