Around the same time the nation was transfixed on the hunt for the Boston Marathon bombers last month, thieves on the other side of the country pulled off a little-noticed heist — swiping 559 pounds of explosives from a federal storage facility in Montana.

As of Friday, not one ounce of it has been found.

The incident, federal officials believe, was not terrorism-related. But it’s the latest to raise security concerns in an age when authorities are warning about the desire of violence-bent terrorists to inflict mass casualties with bombs.

Rep. Steve Daines, Montana’s only congressman, told he’s “deeply concerned” about the theft in his state and will be “closely monitoring” the investigation.

The explosives were stolen from a locked U.S. Forest Service bunker near Billings. Thieves took off with various emulsion-type explosives, cast boosters and detonating cord.