Updated

A spate of attacks on taxis in the Mexican resort city of Acapulco has left 12 drivers or passengers dead, just ahead of Monday's start of the Mexican Open tennis tournament.

Acapulco has been the scene of bloody drug cartel turf wars, and taxi drivers have often been targeted for extortion or recruited as lookouts by the gangs.

The organizers of the largest tennis tournament in Latin America say the Mexican government has pledged that appropriate security measures have been taken for the event.

State police said Sunday that four suspects have been detained in relation with some of the attacks. The suspects had guns, a grenade and a machete that police say may have been used to decapitate some of the victims.