Peruvian police say five nightclubbers are dead after a tear gas grenade was detonated in the middle of a crowded disco.

Police officer Jaime Munoz says nine people including a minor have been arrested on suspicion of setting off the canister in the "Boom" nightclub.

He says the victims died of asphyxiation and seven others were hospitalized in the southern city of Juliaca.

Another police officer, John Mestas, says the tear gas became lethal when released in a closed space with little ventilation.

Mestas told the AP the 800-capacity club had as many as 1,200 people inside when the grenade went off Thursday.

Authorities are investigating how the suspects could have been in possession of the gas.