CNN  — 

A man was killed and three other people were injured after a hand grenade accidentally exploded at a house party in Croatia Saturday, authorities said.

The 25-year-old died after another man, also aged 25, handed him the Yugoslavia-era weapon during the party in the city of Knin, police said.

“Due to improper handling, the grenade accidentally detonated in the hands of the deceased 25-year-old,” the police said in a statement, according to CNN affiliate N1.

A 23-year-old man and a 21-year-old woman also sustained injuries in the blast.

A criminal investigation is underway to determine how the M-75 grenade was acquired.

A large number of weapons ended up in private hands in Croatia following the country’s War of Independence between 1991 and 1995. Parts of the country were also contaminated by landmines after the conflict.

Police in the Sibenik-Knin region, where Saturday’s incident occurred, said more than 5,000 items have been handed to authorities in the region this year alone.