Authorities in the Mexican resort city of Cancun say they are investigating a possible link between a taxi drivers union and organized crime after an attack inside a bar killed seven people, most of them members of the union.

Quintana Roo state Attorney General Gaspar Garcia says the gunmen who burst into "The Little Mermaid" bar specifically targeted union members meeting there Thursday. He says the union's deputy secretary for conflict resolutions was among those killed.

Garcia said Friday that investigators have yet to determine who was behind the attack.

While Quintana Roo has not seen the levels of violence plaguing Mexico's northern border states, it is a major drug trafficking zone.

Several Cancun taxi drivers have been arrested recently for selling drugs or participating in drug-related killings.