The commander-in-chief of the Polish National Police received minor injuries after a gift he received during a recent visit to Ukraine exploded at the police headquarters in Warsaw on Wednesday.

According to Poland’s Ministry of Interior, an “explosion occurred in a room adjacent to the office” of General Jaros?aw Szymczyk, who “suffered minor injuries and has been in the hospital for observation.” The statement described the device as being “one of the gifts the Commandant received during his working visit to Ukraine on December 11-12, where he met with the leaders of the Ukrainian Police and Emergency Situations Service,” but did not specify what it was exactly. A civilian worker at the headquarters was also lightly wounded and did not go to the hospital.

The Ministry added that “The Polish side asked the Ukrainian side to provide relevant explanations. The case has been handled by the prosecutor’s office and relevant services from the beginning.”

Polish media outlet RMF24 reported that the cause of the explosion was from a grenade launcher that was gifted to Szymczyk, which he accidentally fired into another room when showing it off during a meeting, adding that the blast caused parts of the floor to collapse. Polish outlet Onet also reported that “Everything indicates that he accidentally fired the gun, not expecting it to be loaded. The round hit the floor and probably pierced it.”

Ukraine officials have yet to make a statement on the incident.