Commander Fidel Reyna and agent Rene Reyes were ambushed with a spray of automatic rifle fire as they drove their patrol car through the suburb of Santa Catarina late Saturday.

Just hours earlier, Commander Mario Sánchez, 47, was shot dead in San Nicolás de los Garza, one of the nation´s most affluent municipalities.

Gunmen linked to drug-trafficking gangs are increasingly targeting police and soldiers as President Felipe Calderón wages a national offensive against powerful drug cartels.

One person was killed when a group of gunmen attacked a building belonging to the federal Attorney General´s Office (PGR) in the southern state of Oaxaca, police said.

At 8:30 p.m. Saturday, a group of men armed with assault rifles opened fire on the building in the Pacific coast town of Santa Cruz Huatulco.

The victim, according to preliminary reports, may have been on his way to work at the PGR office.

Police said that the gunmen fled the area.

This was the second attack on federal law enforcement agents in Oaxaca since the start of the weekend.

Oaxaca´s public safety secretary, Sergio Segreste, said a man killed Friday night outside the state capital was a member of the AFI.

Last Wednesday, some 50 armed men killed five policemen and two residents in the town of Cananea, near the Arizona border. Police and soldiers chased the assailants into the hills, killing 16 in the ensuing gunbattles.