Authorities in the Mexican resort of Cancun say two gunmen burst into a bar in a working class neighbourhood and fatally shot seven people.

Four others are wounded. Public safety secretary Jesus Aiza says most of the victims belonged to a taxi drivers' union. Aiza says the assailants arrived to The Mermaid bar in a poor area far from Cancun's hotel zone in two cars Thursday afternoon. He says two gunmen using automatic rifles went inside and began shooting.

Aiza says soldiers are guarding the hospital were the wounded are being treated.

He says police are still trying to determine a motive for the attack.