A prosecutor in Mexico said Tuesday the killing of two Canadians at a Caribbean coast resort last week was motivated by debts between international gangs apparently dedicated to drug and weapons trafficking.

On Friday, prosecutors said both dead men had criminal records in Canada, and one was a known felon with a long record related to robbery, drug and weapons offenses. A third Canadian, a woman, was wounded and is being treated at a local hospital, but is not yet able to speak with investigators.

“The investigations indicate that this attack was motivated by debts that arose from transnational illegal activities that the victims participated in,” said Oscar Montes, the chief prosecutor of the Quinta Roo state. “The information (is) that they were involved in weapons and drug trafficking, among other crimes.”

Montes said the attack had been planned for almost a month by a cartel or gang that had not previously been known to operate in the area. But in keeping with standard procedure, he declined to name the gang.

The attack took place Friday at the Hotel Xcaret resort is south of Playa del Carmen. The attackers apparently had guest wrist bands to enter the resort.

Montes said a first group of assassins hired to kill the Canadians earlier in January abandoned the job because there was too much security.

A second assassin flew in to the resort and carry out the killing. Authorities said the two suspects arrested in the case so far are a professional kidnapper from Mexico City who coordinated the plot, and the hired killer.

Police also arrested a female, identified only by her last name, Nu, who was apparently part of the group of 10 Canadians who were vacationing at the resort. Montes said Nu both “cared for the children” of the victims, and allegedly met with the killers and may have been providing them information on their activities.

If Canadian gangs were involved in Quintana Roo, it would not be shocking. The Caribbean coast state, because of its huge flow of foreigners, has seen a number of crime rings with international connections.

A Romanian gang has long operated in the state, using ATM machines to clone credit cards or make illegal withdrawals. And this week authorities arrested two Ukrainians for their alleged involvement in a fuel theft ring. Immigrant traffickers have long used Cancun as base for smuggling Cuban migrants

Last week’s killings were the latest in a series of brazen acts of violence along Mexico’s resort-studded Mayan Riviera coast, the crown jewel of the country’s tourism industry.

In November, a shootout on the beach of Puerto Morelos left two suspected drug dealers dead. Authorities said there were some 15 gunmen from a gang that apparently disputed control of drug sales there.

In late October, farther south in the laidback destination of Tulum, two tourists – one a California travel blogger and the other German – were caught in the apparent crossfire of rival drug dealers and killed.

Following those events, President Andres Manuel Lopez Obrador sent nearly 1,500 members of the National Guard to reinforce security in the area.