A masked gang broke into a beach bungalow at a Mexican tourist hot spot and raped six women after tying up their partners with mobile phone cables and bikini straps.
The gang allegedly attacked the Spanish tourists as they slept in the rented bungalow in Acapulco, CNN reported.
They held the group at gunpoint but spared a Mexican woman who was also staying with the group, officials said.
They also allegedly stole cash, credit cards and mobile phones from the tourists, who were understood to be in their 20s and 30s.
Acapulco mayor Luis Walton apologised for the incident at a media conference and said it would probably affect the image of the tourist destination.
"We are going to have the full weight of the law against those responsible," he said.
"We know that it's very unfortunate what happened, but hey, it happens everywhere in the world."
Acapulco, generally considered a relatively safe destination, has faced fiscal troubles and an increase in violent crime since the global financial crisis, CNN reported.
Author: Alexandra Pleffer, Approving editor: Mark Worley