WARSAW, Poland (AP) — A gift that a Polish police commander received during a recent visit to Ukraine exploded at police headquarters in Warsaw, causing the commander and a civilian employee to suffer minor injuries, the Polish Interior Ministry said Thursday.

The explosion occurred on Wednesday morning at 7:50 a.m., the ministry said. It did not specify what object the Polish commander received as a present during the working visit to Ukraine.

The commander met with leaders of the Ukrainian Police and Emergency Situations Service on Sunday and Monday, the ministry said.

Following the explosion, “the Polish side has asked the Ukrainian side to provide relevant explanations,” it said.

It added that the police commander has been in a hospital since Wednesday for observation, while the civilian employee did not require hospitalization.

Poland is an ally of Ukraine and has been offering it different forms of support since Russia’s full-scale invasion on Feb. 24. Poland has sent military and humanitarian aid to Ukraine and accepted large numbers of refugees.