said.

Seven men who were with the group were tied up with cell phone cables and bikini straps while the gunmen assaulted the six women, officials said.

A seventh woman, a Mexican, was spared because of her nationality, Guerrero state Attorney General Martha Garzon said in a radio interview.

"She has said that she identified herself to the men and asked them not to rape her," Garzon told Radio Formula. "And they told her that she had 'passed the test' by being Mexican, and from that point they don't touch her."

The gunmen's motive was robbery and "to have some fun," as they saw it, Garzon said. They do not appear to be a part of organized crime, officials said.

Military checkpoints have been set up to apprehend the suspects.

As they sift throughevidence, investigators have cordoned off the area around the bungalow, which is in an open area of Playa Encantada that has limited security in Playa Encantada.

Last year, the city of Acapulco attracted half a million tourists -- most of them Mexicans.

Mexico's Foreign Ministry said in a statement that the Spanish tourists received consular aid after the incident.

The U.S. State Department says "resort areas and tourist destinations in Mexico generally do not see the levels of drug-related violence and crime reported in the border region and in areas along major trafficking routes."

But the agency adds that resort city bars, including those in Acapulco, can be "havens for drug dealers and petty criminals."