A military armory at Tancos Air Base, about 60 miles North of Lisbon, Portugal had a break-in on Wednesday in what local defense officials are referring to as a “very professional” job and a “serious” breach of security.

Although the Portuguese military has been clear that they do not intend to release the details of the incident until the investigation has concluded, they have provided an overview of the circumstances surrounding the incident.

Sometime on Wednesday, individuals were able to gain access to Tancos Air Base by cutting a hole in the base’s perimeter fence.  They went on to gain access to one of Portugal’s armories within the installation and steal a large number of various sorts of grenades and other explosives, as well as nearly 1,500 rounds of 9-millimeter ammunition.

The armory had no operational electric security or surveillance equipment, and was guarded by military police patrols.  Reports indicate that there are closed-circuit cameras at the site, but they have been broken for over two years.