By Brendan O'Brien

(Reuters) - An explosion in a grain silo killed an employee at an agricultural co-op in rural northwestern Indiana on Monday, authorities said.

James Swank, 67, of Union Mills was killed in the afternoon explosion at the Co-Alliance fertilizer and grain facility in Union Mills, some 70 miles southeast of Chicago, the LaPorte County Sheriff's Department said.

The cause of the blast was unknown.

Initially, the Sheriff's Department said the explosion was at a fertilizer plant. Later, Shawn Lambert, the safety and risk manager at Co-Alliance, said the explosion happened in a grain silo at the facility.

"We pride ourselves on safety and we are very saddened by the fact that we lost somebody," Lambert said.

It was unclear where Swank was working when the blast occurred in the concrete grain silo adjacent to a railroad spur, Lambert said.

"There is some uncertainty as to whether he was on top of the roof or in the ground level section," Lambert said.

All others who were at the plant at the time of the explosion were accounted for, LaPorte County Sheriff's Deputy Neil Lachmund said.

No hazardous chemicals were involved or released as a result of the explosion and no fire was detected, the department said in a Facebook post.

Two months ago, a fertilizer plant explosion in West, Texas, killed 14 people and injured about 200.

Less than two weeks ago, an explosion and fire killed one person and injured 73 at the Williams Olefins chemical plant in Geismar, Louisiana.

(Reporting by Brendan O'Brien; Editing by Daniel Trotta and Mohammad Zargham)

["Silver Silos In The Field" on Shutterstock]