PARIS — Police in Geneva were “actively searching” for suspects in connection with last month’s Paris attacks, Swiss security officials said Thursday.

Authorities got word Wednesday that federal officials had flagged that “several suspects were likely in Geneva or in the region around the city,” according to a statement issued by the city’s department of security.

Police were boosting the threat level and reinforcing “agents on the ground,” the statement said. Authorities did not specify how many people were being sought or their identities.

“In light of the international and national investigation that followed the attacks in Paris, the police department in Geneva is actively searching for several individuals,” the statement added.

U.N. security guards in Geneva, the European headquarters of the world body, were stationed with MP5 sub-machine guns at entry points for cars, a highly unusual measure at the sprawling complex near the French border.

Related: Bataclan Attacker’s Mom Got ‘Martyr’ Text Message

A security guard at the U.N. site told Reuters that Swiss authorities were searching for four people believed to be in the city, or nearby. Another guard said the U.N. compound was on maximum alert. NBC News was not immediately able to independently verify that report.

Shooting and bomb attacks claimed by ISIS killed 130 people in Paris on Nov. 13. Police in several European countries are still searching for individuals believed to have been involved in the attacks or in their planning.