CHICAGO (AP) — Twin derailments of commuter trains this week were accidents and unrelated to suspected sabotage along the same line last week, authorities said Wednesday.

Metra determined that heavy vehicular and train traffic caused a slight separation between the tracks, leading to Tuesday night's derailments of the slow-moving trains near a busy crossing. The cars remained upright and no injuries were reported.

"We can say with absolute certainty there was no foul play involved, no tampering to any extent," Metra spokesman Judy Pardonnet said. "It was a strange situation where two trains derailed on two separate tracks at the same location."

Normal service was restored for the morning rush.