At least four people were hurt in a house explosion Monday afternoon. Several fire departments responded just before 4 p.m. to the site in the town of Grant. Officials said four people were taken to hospitals via helicopter for their injuries. Sheriff's detective sergeant Gordon Kowaleski says the names and ages of the injured aren't being made public right now. He didn't know their conditions. It could take a while to determine the cause, officials said. "It's a fire scene. There's a lot of damage to the house. I'm not going to comment past that until we get the fire marshal up here and we can thoroughly look at the scene and try to figure out what happened," Kowaleski said. Emergency vehicles blocked the road for more than four hours, but by 8:30 p.m. all firefighters and rescue crews had left. Investigators will return Tuesday as soon as there’s daylight. The sheriff’s office remained to secure the area and make sure no one goes onto the property.