CANCUN, Mexico -- Gunmen attacked the state prosecutors’ office in this Caribbean resort city Tuesday, and authorities said four people were killed, ratcheting up tensions just a day after a shooting at a music festival in a nearby town left three foreigners and two Mexicans dead.

It was too early to say if the attacks were linked, but they were a marked intrusion of bloodshed into Mexico’s main tourism zone, a region that had previously been spared much of the violence plaguing other parts of the country.

The governor of Quintana Roo state, Carlos Joaquin, said three attackers and one police officer died in Tuesday’s incident. He said five suspected attackers were taken into custody. He urged calmed, saying the federal government was sending more security forces to the region.

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A witness said the attackers also tossed two explosive devices at a perimeter wall. A reporter at the scene saw police remove a body from a guard post near the building after the attack.

Earlier in the day, the hypothesis of drug links to the shooting in nearby Playa del Carmen before dawn Monday was strengthened after a banner briefly appeared along a roadside, signed by the “Old School Zetas,” part of the fragmented Zetas cartel, suggesting the attack was carried out as part of a battle against rival gangs.

Quintana Roo’s attorney general, Miguel Angel Pech, said investigators were looking into whether the banner referred to the BPM music festival or one of its organizers.

Pech said authorities were investigating whether extortion, street-level drug sales or a murder plot was the motive behind the shooting at the closing party for the BPM electronic music festival. Five people died and 15 suffered injuries.

Pech said the gunman fired directly at one of the Mexican victims at the Blue Parrot nightclub where the 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, Pech said. It was unclear why the Mexican man might have been a target. Pech said his family told prosecutors that he had “an important relative” in the state government of Veracruz, a state plagued by corruption and violence.

A Denver teen was among the dead, CBS Denver reported. Alejandra Villanueva’s family said she was among those who were trampled, the station said.

The attacker fled, but Pech told the Televisa TV network that a taxi driver who helped the man escape has been linked to previous extortion attempts. Some businesses in Mexico are forced to pay protection money under threat of being attacked.

“Either they didn’t reach an agreement over protection payments, directly extortion, or it may be that somebody did not allow them to sell drugs inside” the nightclub, Pech said.

“Perhaps the strongest hypothesis is that this person had gone there to demand they comply with protection payments,” he added at a news conference.

A forensic investigator walks inside the Blue Parrot club, one day after a deadly early morning shooting in Playa del Carmen, Mexico, Tuesday, Jan. 17, 2017. Rebecca Blackwell, AP

Playa del Carmen residents said the shooting came amid a growing and increasingly open drug scene in the resort town, which has long been spared the violence of Mexico’s cartel wars.

Concerns that violence may be creeping into the once-tranquil beachside town were voiced as people attended a Monday evening vigil in front of the Blue Parrot nightclub.

“This is a sign of what has been happening,” said Lenin Amaro, a local business owner and politician.

“It has reached us,” Amaro said of the country’s drug violence. “We were living in what you could call a bubble.”

Federal authorities say the Zeta cartel has been in the state for years, especially in Cancun itself, where the Zetas were blamed for the firebombing of a bar in which eight people died in 2010.

And drug cartel influence in the state as a whole goes back at least to the 1990s under Gov. Mario Villanueva, who was later convicted in the U.S. of involvement in large-scale drug smuggling.

