HUMBOLDT, S.D. (KELO) — One man is dead and another man and woman are hurt following a house explosion that could be felt from miles away.

It happened south of Humbolt, just west of Highway 19, Wednesday morning.

The two victims who survived had to be taken to the hospital by helicopter.

Investigators continue to sift through the debris looking for answers as to what caused the house to explode.

“There’s a chance it exploded shortly after 5 this morning,” Minnehaha County Sheriff Mike Milstead said.

There is nothing left of this house.

It was flattened by an explosion.

Someone driving by called 9-1-1 about two hours later and immediately responded on his own.

“Passerby was able to pull a couple of the residents to safety until deputies and firefighters arrived,” Milstead said.

Responding to an emergency like this one can take an emotional toll on first responders, especially in rural areas where everyone knows everyone.

“The difficult thing in these situations you know these are volunteer firefighters who are responding and volunteer ambulance; they are all neighbors they are all friends, they know who lives there so, you know they train every day for this, but it’s hard to train and understand what it’s like to respond to someone who is your close friend or a co-worker or a relative and that’s what we had in this situation,” Milstead said.

They allowed our cameras to get a little closer than where we were this morning. If you look behind me you can see debris strewn about a half mile away. The explosion was so loud some people reported hearing it 18 miles away.

Some people thought it was thunder because there was rain in the forecast, but they now know that thunderous sound was a house exploding.

Counselors are being made available to help anyone of the first responders, including the passerby who reported the incident and pulled two of the victims from the debris.

It’s the fifth house explosion we’ve reported on in South Dakota this year.