PLAYA DEL CARMEN, Mexico — Mexican authorities said Tuesday they are investigating whether extortion, street-level drug sales or a murder plot was the motive behind a shooting at an electronic music festival at a Caribbean resort town that left three foreigners and two Mexicans dead.

The attorney general of Quintana Roo state, where Playa del Carmen is located, said the gunman fired directly at one of the Mexican victims at the nightclub where the festival’s closing party was being held. A confused shootout ensued in which guards — it is not clear whether festival security personnel or the Mexican’s bodyguards — returned fire.

One guard was hit by gunfire, and as he fell, his pistol went off, wounding several concert-goers, according to state Attorney General Miguel Angel Pech. It is unclear why the Mexican man may have been a target.