At least one person was injured when a letter sent to the International Monetary Fund office in Paris exploded upon opening, reported AP. Investigators said the IMF office had received several threat calls prior to Thursday’s incident, though they have yet to confirm if the letter was related to the calls. The police have not revealed the identity of the sender so far.

“I have been informed about the the explosion in the IMF’s Paris office, which caused injuries to one of our staff,” said IMF chief Christine Lagarde. “We are working closely with the French authorities to investigate this incident and ensure the safety of our staff.” French President Francois Hollande said, “We are again confronted with an attack. There is no other word for it when you are confronted with a package bomb.” The office is on the Avenue Iena near the Champs Elysees.

This comes only a few weeks before the French presidential elections, which will begin on April 23. Europe has been wary of terror attacks in the past two years, with France still being in a state of emergency after a series of attacks. On Wednesday, a Greek militant group sent a parcel bomb to German finance minister Wolfgang Schäuble. However, it was destroyed before it could explode.