A car bomb has exploded outside the local affiliate of Televisa TV network in the northeastern city of Ciudad Victoria.

Friday's blast damaged equipment and the station was unable to broadcast locally, AFP news agency reported.

"Fortunately none of our colleagues were wounded," Carlos Loret de Mola, the host of the Televisa morning news show, said.

Two witnesses saw the charred remains of a parked vehicle outside the TV studio in the city in Tamaulipas state and Televisa's main morning news anchorman said nearby buildings were damaged, causing a power outage.

Televisa, Mexico's most watched TV network, has had affiliates attacked twice this year, most recently in the northern industrial city of Monterrey two weeks ago.

A van packed with explosives blew up outside a police station on August 5 also in Ciudad Victoria, causing some damage but no injuries.

Similar attacks

No group was immediately blamed for the blast but drug cartels set off a car bomb in Mexico's most violent city, Ciudad Juarez, in July, the first of its kind, and another earlier this month in Tamaulipas in Mexico's escalating drug war.

Ciudad Victoria is the capital of Tamaulipas state, which borders the US state of Texas.

The Gulf of Mexico drug cartel has been engaged in a bitter turf war for control of Tamaulipas smuggling routes into the US with the Zetas drug cartel.

On Tuesday, Mexican authorities found 72 bodies at a Tamaulipas ranch that police believe belong to illegal migrants from Central and South America. Authorities blamed the Zetas cartel.

An injured Ecuadoran man claiming to be the sole survivor of a massacre alerted the military and said the migrants had been kidnapped and killed for refusing to work for the Zetas.

Mariana Sanchez , Al Jazeera's correspondent in Mexico, said that while the channel suffered attacks in the past, this one is significant.

"It happened just days after the massacre [of 72 people]. It appears to be a message from the perpetrators, the Zetas, that they are in command here and they don't want any investigating to be done in Tamaulipas state," Sanchez said.

More than 28,000 people have been killed in drug-related violence since December 2006, when Felipe Calderon, Mexico's president, launched a nationwide crackdown against narco-traffickers.