Photo: Grupo Reforma
No one was hurt when an assailant in a passing vehicle hurled a grenade at a bureau of El Norte newspaper in the northern Mexican metropolis of Monterrey.
"The grenade detonated in a window box located 3 meters (10 feet) from the main door of the installation, causing damage only to two windows," the daily said on its Web page.
Soldiers and police moved quickly to cordon off the area after the blast, El Norte said, noting that Thursday night's attack was the third on the same bureau since last September.
Neither of the two earlier assaults caused any casualties.
Conflict among rival cartels and between criminals and the security forces have claimed some 35,000 lives in Mexico since December 2006, when newly inaugurated President Felipe Calderon militarized the struggle against the drug trade.
Until last year, however, drug-war mayhem was comparatively rare in Greater Monterrey, home to more than 4 million people and the headquarters of many of Mexico's leading corporations.
The city and the surrounding state of Nuevo Leon are now a main battleground in a vicious turf batter between the Gulf and Los Zetas drug cartels.
The cartels often target media outlets and individual journalists, and routinely resort to threats and bribery to influence press coverage of their activities.
Nine reporters were killed last year in Mexico and four went missing, while 64 journalists filed complaints with the National Human Rights Commission, Mexico's equivalent of an ombudsman's office, over attacks and aggressions.
The commission says 66 journalists have been slain in Mexico since 2000 and the vast majority of those murders remain unsolved.