The Louvre reopened today after being unexpectedly forced to close yesterday when between 100 and 200 security workers walked out in protest of the gangs of pickpockets running wild in the museum’s galleries and threatening staff, and the institution has pledged to deploy a stronger police presence. The museum received some 150 specific complaints from unionized security staff regarding the gangs of thieves, AFP reports.

“There have always been pickpockets at the Louvre and in tourist destinations in central Paris,” Louvre security agent and union member Sophie Aguirre told AFP, “but for the past year and a half they have been more and more violent, numerous, and their operating methods more sophisticated.”

Yesterday a group of some 100 security agents went to the France’s culture ministry, and a delegation was received by the minister of culture, Aurélie Filippetti. According to the ministry of culture Filippetti then contacted the minister of the interior, Manuel Valls, “to put in place a security protocol specifically tailored to this unacceptable situation, and additional police forces outside the museum.”

Such steps may prove futile, however, as many of the pickpockets in question, according to museum security guards, are children of Eastern European descent who enter the museum for free in groups of as many as 20 or 30. The Louvre currently employs some 1,000 security guards and surveillance agents, roughly 470 of whom are typically working at any given time.