CENTERVILLE, Iowa (AP) — Authorities say two bodies were found in a rail car that had carried about 100 tons of steel from Mexico to south-central Iowa.

The Daily Iowegian newspaper reports that Iowa Southern Railway workers discovered the bodies Friday when decoupling cars from an engine about 1.5 miles (2.4 kilometers) southeast of Centerville. The cars had been pulled there Friday after BNSF railroad dropped them off Thursday in Albia.

Authorities think the two people were killed by the tons of shifting steel that had been loaded in Monterrey, Mexico. It’s unclear when they got into the car.

The pair have yet to be identified. The bodies were taken to the Iowa state medical examiner’s office.