At least 45,000 people have died in drug-related killings since President Calderon launched a war on gangs in 2006

Armed men have opened fire on a group of volleyball players in the Mexican state of Sinaloa, killing eight people and wounding at least seven, authorities say.

Francisco Cordova, head of Sinaloa state police, said on Saturday some of those killed were playing volleyball while others were watching. The volleyball court is in a working-class neighbourhood of Culiacan, the state capital.

It was not immediately clear whether the shooting was drug related, but Sinaloa is the home state of Joaquin Guzman's powerful drug cartel. It has been the scene of bloody battles between the gang and its rivals.

Marco Antonio Higuera, Sinaloa prosecutor, said while it had not been ruled out that the volleyball players and spectators were caught in a crossfire, witnesses told authorities the assailants arrived accompanied by two people with covered faces who pointed out to the assailants who to shoot.

Higuera said the attackers "knew perfectly who they were going to kill'' and that the attack was part of a conflict between rival groups.

Drug-related violence is almost daily occurrence in Mexico, with cartels battling for control of territories particularly close to the US border.

Ciudad Juarez shootout

Groups of heavily armed men fired hundreds of shots at each other on Thursday in the streets of the border city of Ciudad Juarez, leaving at least six dead.

Arturo Sandoval, a spokesman for Chihuahua state prosecutors, said the shooting took place in a rough part of the city. He said investigators recovered 442 spent bullets from the scene.

Ciudad Juarez is considered one of Mexico's most violent cities, with nearly 10,000 drug-related deaths in the last five years.

The recent violence comes as Mexican police arrested the alleged leader of the La Barredora drug cartel, believed to be partly responsible for the recent upswing in abductions and murders in the resort city of Acapulco on the Pacific coast of Mexico.

Under heavy security, police showed Victor Manuel Rivera Galiana, known as "Victor, El Gordo" (Victor, the Fat Man), to journalists at a Mexico City news conference.

Ramon Eduardo Pequeno, a federal police official, said that Rivera Galiana, who was arrested on Friday, was one of three founders of La Barredora.

About 45,000 people have died in drug-related killings in Mexico since President Felipe Calderon launched a war on the drug gangs shortly after taking office at the end of 2006.