Fire officials continue investigating cause of explosion in Ypsilanti Township

Fire crews are surveying the damage in Ypsilanti Township, Michigan, after a major explosion on Wednesday, Feb. 18, ripped through an electronics printing business. 

"The structure of the building took a considerable hit with the blast," said Ypsilanti Fire Marshall Steve Wallgren. 

Authorities say a blast rocked the Electronics for Imaging building on James L Hart Parkway. Wallgren said the official cause of the blast is still under investigation, but he confirmed an initial gas leak caused most of the workers to evacuate before the explosion. Thankfully, there wasn't a lot of fire that accompanied the blast. 

"There's not a lot of flammable material in there, even though the chemicals they use for dye making, you know, certain, the manufacturing process aren't highly flammable, so that was lucky for us," he said. "There wasn't a lot of fire load, but the sprinkler system was working as well." 

On Thursday, CBS News Detroit talked with employees at Restaurant Depot, the business next door to the printing business, who declined to do an interview but said they heard and felt the explosion. They said they wanted to help in any way they could and watched as workers next door evacuated, even dragging people from the wreckage with broken legs and serious burns. 

"All handled by fire crews and HVA on scene and got them to some of the best hospitals in the state," Wallgren said. 

Members of Electronics for Imaging declined an interview on Thursday but confirmed that three people were taken to the hospital on Wednesday. Since then, one was released, and two remain getting medical treatment. Their current conditions are unknown.

"... We remain in close contact with the affected individuals to provide appropriate support during this time.  Our first concern is always the safety and welfare of our people and community," said Holly O'Rourke, the director of corporate communications for Electronics for Imaging.

Wellgren said it's unclear how long the building will be closed. 

"That really was what drove today's, getting people inside so engineers can have a look at it and determine what it's going to take to get this building back up and running. They're all optimistic, though," he said.