FREDERICK, Md. — An overnight fire at a UPS center in Maryland has sent a yet undetermined number of packages up in smoke during this holiday season.

WUSA-TV reports Frederick County Fire Department spokesman Kevin Fox says the fire was reported about 11:40 p.m. Monday.

News outlets report responding crews found 10 trucks and a package loading structure ablaze.

Fox says it took firefighter around 45 minutes to bring the blaze under control. He says the building suffered mostly exterior damage since a sprinkler system activated inside the main structure.

The Fire Marshal is investigating the fire’s cause.

A representative for UPS says the company is working to identify and notify shippers of the damaged packages, as well as reroute packages that would have gone out on the damaged trucks.