Gunfire broke out on a beach in Mexico’s Caribbean coast resort of Cancun Tuesday, sending tourists scrambling for cover, but authorities said nobody appeared to be injured.

Lucio Hernandez Gutierrez, the chief of police of the coastal state of Quintana Roo, said the attackers apparently pulled up to the beach on jet skis and opened fire at a beach in Cancun’s hotel zone. Hernandez Gutierrez said the jet skis had been found and seized.

One witness to the attack, Rick Lebassa, a tourist from Maine, said two or three gunmen appeared to be shooting into the air with pistols, not at the beach.

“There were two guys and maybe even a third, who came in on jet skis, and what I saw was them shooting up into the sky,” Lebassa said. “I did not see any shots coming in toward the shoreline.”

Lebassa says this was the first incident of this kind he’s seen in his 31 years of coming to Cancun.

“I’m not overly concerned because this is the first time ever,” Lebassa said. “We’ve been coming down for 31 years and we’ve never had any issues.”

The shooting is the latest in a string of violent incidents on the resort-studded coast, and came in the same week that a special battalion of National Guard troops were assigned to protect the area. Mexican marines with bulletproof vests, helmets and assault rifles were seen patrolling Cancun’s tourist-crowded beaches following the Tuesday shooting.

On Nov. 5, a commando of drug gang gunmen stormed a beach at Puerto Morelos, a resort just south of Cancun, and opened fire in front of luxury hotels, executing two drug dealers from a rival gang. The dramatic shooting attack sent tourists scrambling for cover.

State authorities called it “a clash between rival groups of drug dealers on a beach” near two hotels. Several cartels are fighting for the area’s lucrative retail drug trade, including the Jalisco cartel and the a gang allied with the Gulf cartel.

The shootings were the latest chapter in drug gang violence that has sullied the reputation of Mexico’s Caribbean coast as a once-tranquil oasis.

The administration of President Andres Manuel Lopez Obrador has pinned its hopes on the so-called Maya Riviera, where it has announced plans to build an international airport and a stop for the Maya train, which will run in a loop around the Yucatan peninsula.