Mexican marines exchanged gunfire with a group of gunmen in Mexico's Baja California Sur state, leaving seven dead, officials said on Sunday.The state's Attorney General's Office (PGJE) said the clash took place late on Saturday in the popular beach resort of Los Cabos, as the marines headed to a neighborhood in San Jose del Cabo, one of two towns that comprise the resort, to investigate the sound of gunfire.On the way, the marines detected armed men riding in two vehicles, both with US license plates, in the road ahead of them and ordered them to stop, but they sped up in an attempt to flee while the occupants fired their guns.As the chase continued, both vehicles eventually crashed into walls or barricades, though the four occupants of the second vehicle got out and continued to fire on the marines until they were killed.Marines seized high-caliber weapons and vehicles in the operation.The PGJE said it opened an investigation into the incident it said was "allegedly linked to criminal events that have taken place in the state."In late December, authorities found bodies hanging from bridges near Los Cabos, in a sign that violent crime sparked by rival drug trafficking organisations is plaguing the state.