Gunmen attack Mexico TV station

Masked gunmen in Mexico have fired several shots and thrown a grenade at a television station as it broadcast its main evening news bulletin.

No-one was injured in the attack on the Televisa network's station in the northern city of Monterrey.

A message was left warning the station about its coverage of drugs violence.

Since 2006, 15 journalists have been killed in Mexico and many local newspapers have stopped investigative reporting of the drugs cartels.

This attack is believed to be the first on a Mexican TV station.

The Televisa network was broadcasting its main evening news bulletin when a presenter announced that the station was under attack.

Outside, two cars had pulled up. Several gunmen wearing ski masks sprayed the main entrance to the building with bullets.

A grenade was also thrown which exploded in an empty workshop.

A note was left nearby, reading "Stop just reporting on us, report on the narco's political leaders" - an apparent reference to the Mexican government.

President Felipe Calderon has vowed to destroy the cartels which make billions of dollars trafficking cocaine and other drugs to the United States.

The strategy has led to spiralling violence - with cartels fighting both each other, and government forces.