(REUTERS) - An employee at an agriculture co-op was killed on Monday by an explosion in a grain silo in rural north-western Indiana, local authorities said.

The explosion occurred at about 1.30pm (2.30am in Singapore) at the Co-Alliance fertiliser and grain facility in Union Mills, the LaPorte County Sheriff's Department said.

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

The employee was working in the concrete grain silo that is adjacent to a railroad spur at the time of the blast, according to a post on the department's Facebook page. No other information was released on the employee.

All others who were at the plant at the time of the explosion have been accounted for, according to LaPorte County Sheriff's deputy Neil Lachmund.

Mr Lachmund said the cause of the blast is unknown.

No hazardous chemicals were involved or released as a result of the explosion and it is not believed that a fire was involved, the post said.

The facility is about 113km south-east of Chicago.

Two months ago, a fertiliser 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.