Perhaps this is a random theft by opportunists, but my guess is that this was probably an inside job:

Part of a shipment of semiautomatic assault rifles was stolen this week from a freight train container at a rail yard in Chicago’s Englewood neighborhood, federal authorities and a railroad spokesman said.

The 13 Smith & Wesson M&P15 Sport rifles were stolen from a yard located in the 6100 block of South Lafayette Avenue sometime between Sunday and Tuesday, a spokesman with the federal Bureau of Alcohol, Tobacco, Firearms and Explosives said.

“We’re hoping to recover them before they’re … used in any type of crime,” said Special Agent Thomas Ahern, spokesman for the ATF’s Chicago field office.

The assault rifles were taken from a load of 50 weapons in a Norfolk Southern container, said a railroad spokesman, who declined to comment further, citing the ongoing investigation. The Chicago Police Department said it could not find any information about the theft.

There was a much larger hit of 120 AK-style rifles in Atlanta in 2012, and I’m not having any luck discovering if they were ever recovered. If you have any recollection of that theft, or know if the thieves were ever arrested, I’d love to hear about it in the comments.

In most instances of gun theft in shipping, it seems that contract security are the usual suspects. It will be interesting to see if that turns out to be the case in this latest theft as well.