Postville, Iowa saw rescue crews swarm in early this morning after an explosion rocked a laminate plant.

As of now, it’s unknown what caused the explosion at Norplex-Micarta, though an investigation is ongoing. Three people were injured in the blast; one critically so, and had to be taken by helicopter to Iowa City, where there is a hospital with a special burn unit.

The building was full of flammable materials which had to be contained by officials so smaller fires wouldn’t start; luckily, the first explosion set off the sprinkler system, which helped fire fighters in their efforts. Investigators estimate the damage at around $5 million. Plant manager Alan Johnson released a statement, saying, “We are waiting for further updates. Our prayers are with our employees and their families.”

The fire is the latest in a string of explosions around the country; last week, a blast took out a chemical factory in Geismar, Louisiana, killing at least one person and injuring more than sixty. Just a few days ago, an explosion at a nitrogen plant in Donaldsonville, Louisiana killed one person and left seven more injured. A gas leak in Westminster, Colorado injured two and severely damaged several homes last week.