Thieves who stole seven paintings from a Rotterdam museum took advantage of an automatic door-unlocking system.

According to an AP report, the Kunsthal museum was responding to criticism after thieves broke in last week and grabbed works worth millions by Picasso, Matisse and Monet, among others.

The museum said that it uses an electronic locking system that is activated after an alarm is triggered, but deactivates again shortly afterward for safety reasons. The report says that thieves waited until the electronic system deactivated, broke a physical lock on an emergency door, and were in and out in less than two minutes. Police arrived in five. The report says that the police have no suspects.