We have three reports about the same story out of Johnson, Iowa. Work progressing at the Summit Middle School in Johnson caused a blast or small explosion, followed by what sounds like a small fire from some flammable adhesive igniting, exploding and then catching fire. The two workers apparently were using a cutting torch and suffered minor burns requiring medical attention at a local hospital. The work was construction of an exterior wall in new construction.
See 2 workers hurt in small blast at Iowa school, Channel 12 Fox, Mankato.
Quad-City Times article with the exact same title.