PUERTO VALLARTA, Mexico -- Mexican authorities say at least 16 people have been injured by a grenade that exploded at a bar in the resort city of Puerto Vallarta.

Jalisco state prosecutors say five of the injured have been detained as part of the investigation. Four of those detained each lost a leg in the explosion before dawn Thursday.

Prosecutors say they are investigating whether one of the injured was carrying the grenade when it exploded.

Jalisco state has seen a wave of drug violence in recent months and the bloodshed has intesified since drug kingpin Ignacio "Nacho" Coronel was killed by soldiers earlier this month. Coronel, whose base was in Jalisco, was the No. 3 of the Sinaloa drug cartel.