Police in Geneva have heightened security and are “actively searching” for suspects involved in the November 13 terror attacks in Paris, officials said on Thursday. The authorities said they were tipped off on Wednesday that federal officials had flagged “suspicious individuals susceptible to being in Geneva or the Geneva region,” the Associated Press reported.

A statement issued by Geneva’s department of security affirmed that police were on high alert. “The Geneva police...have increased their level of vigilance and reinforced the number of police agents on the ground,” the statement said, although it did not specify how many people were being sought or their identities.

A security guard in the United Nations’s premises in Geneva told Reuters that Swiss authorities were on the hunt for four suspects believed to be in the city. Armed UN security guards were stationed at entry points for cars and were on maximum alert.

On November 13, Paris was hit by a series of coordinated terror attacks, which left as many as 130 people dead. Considered the deadliest attack on France since World War II, for which the Islamic State militant group claimed responsibility, they involved suicide bombings and mass shootings at restaurants, cafes and other venues across the city, including the Bataclan music hall and the Stade de France stadium.