GARY, Ind. -- The bodies of two people were found Sunday in a 15-foot (5-meter) high pile of manure at a horse farm in Gary, Ind.

Police said a man boarding his horse at the stable called authorities at about 10:30 a.m. after spotting what he thought was an arm sticking out of the pile, The Times of Northwest Indiana reported.

Gary Police Cpl. Mike Barnes said: "As we were uncovering the first body, we came across a second body also in that pile."

Both bodies, one of which was a man, were wrapped in plastic, the Chicago Sun-Times reported.

It is not yet clear how they died, police said.

"If somebody is missing, [family or friends] are more than welcome to call," Barnes said. "We don't have the two people identified yet and we have no idea who they are at this point."

Officials carefully searched the rest of the manure pile to ensure no other bodies were hidden.

Gary is a city in Lake County, northwestern Indiana, but is only 25 miles (40km) from downtown Chicago.