LACROSSE, Ind. — Three of the four people injured in a Co-Alliance grain elevator blast in northwestern Indiana remained hospitalized a week after the April 16 explosion. In addition, work was still ongoing to stabilize the 175-foot-tall feed mill so investigators can safely go inside the concrete structure and begin looking for a cause of the explosion.

"It’s still got some debris hanging from it and it’s got some structural stuff that needs to be shored up and taken care of before it’s deemed safe enough to go in to start the investigation (perhaps this week)," said John Graham, chief financial officer for Co-Alliance, the owners of the grain elevator.

Graham works out of the Co-Alliance headquarters in Avon, west of Indianapolis. The company has 11 feed mills in the northern and central parts of Indiana and one just south and west of Buchanan, Mich., at 16724 Bakertown Road.

Jonah Pacione, 19, and Emilio Galicia, 34, remained at the St. Joseph Burn Center in Fort Wayne. Pacione was still listed in critical condition at press time "but he’s improving,’’ said Sheryl Mourey, the burn unit’s nursing supervisor.

Galicia was in serious but stable condition. "Both of these gentlemen are doing much better," said Mourey.

Chris Fort, 26, was taken to Porter Regional Hospital near Valparaiso and later was transferred to the Loyola Burn Center in Chicago where he was listed Thursday in good condition. Craig Chase, 34, was released from Porter Regional several hours after the explosion.

‘’They’re getting the best care we can get them at this point,’’ said Graham.

About half of the concrete feed mill operation on the east side was blown off in the blast, while damage to the east side of the structure was less extensive, but toward the top there was a gaping hole. Five days after the explosion, firefighters were called back because of some still-smoldering grain in the basement that flared up during a period of steady 40 mph winds.

"There was no real danger but there was some smoke and a small fire that had to be put back out," said Graham.

The mill grinds corn and after other ingredients like soybean meal and vitamins are added, the mixture becomes feed for hogs and other livestock at farms primarily within a 50-mile radius.

Among the things that have to be done before going inside is knocking down a partially collapsed wall and cutting down some of the concrete chunks and other debris still hanging off the facility. "How unstable it is, we’re not sure," said Graham, who noted the State Fire Marshal’s Office will decide when the building is fit to be entered.

A decision to close the grain elevator and merge the operation with a new feed mill 40 miles to the south in Reynolds had been made prior to the blast. Most of the employees in LaCrosse will be placed at other facilities owned by Co-Alliance, officials said.

In 2013, a Co-Alliance grain elevator in nearby Union Mills exploded, causing 67-year old James Swank to fall over 100 feet from a work platform to his death. A mechanical failure generating sparks that ignited grain dust was ruled as the cause. The Union Mills grain elevator was rebuilt and is still undergoing improvements.

Graham said it might take several weeks to come up with an official cause of the blast in LaCrosse.