NEW LONDON - The gas leak explosion at Minnehaha academy in Minnesota was so powerful, the center of the building was reduced to rubble. Several summer programs were taking place inside. Mostly everyone got out, but seven people were taken the hospital. A few suffered serious injuries. What happened to Minnehaha is something Jerrall Herron knew all too well. The history of London high school is kept in a museum where he educates visitors.

On March 18, 1937, Lemmie Butler the instructor of manual training, turned on a sanding machine. Unknowingly, the room was filled with an odorless gas.

"Sparks from the electric sander is what set it off," Herron said.

Immediately after the explosion: the walls collapsed, the roof fell in and buried the teachers and students. 14 teachers and 311 students died from the explosion. School records were destroyed and it's believed more than 500 students were killed.

Soon after, a new law was made to a chemical in gas to make an odor. Thus, changed the way natural gas is processed nation wide.

The history of London high school resonated with John Davidson. His sister, whom he never met, died from the explosion.

"I know some day I'll meet her," Davidson said. "And we'll have a lot to talk about."

Across the street from the museum is the revamped version of London high school, which serves as a reminder to people like Herron and Davidson to keep its history alive.