Three senior policemen killed in Mexico border city

A federal police agent stands guard at a checkpoint in the border city of Tijuana April 17, 2007.

TIJUANA, Mexico (Reuters) - Suspected drug gunmen killed three senior policemen and some of their relatives in the Mexican border city of Tijuana, a week after the government beefed up security against drug gangs, police said on Tuesday.

Two of the officers were gunned down while driving near a mall in the city's southern La Mesa district. Another policeman was shot dead at home along with his wife and 9-year-old daughter. Police believe the same gunmen were responsible for the killings.

Mexico last week sent hundreds of police reinforcements to Tijuana following a recent rash of drug killings. It is the biggest city in Baja California Norte, which is Mexico's most violent state with more than 400 gangland-style murders in 2007.

President Felipe Calderon has been battling organized crime since he took office a year ago and has sent some 25,000 troops and federal police to the country's worst trouble spots.

On Monday alone, 17 people were found dead across the country in drug-related crimes, Mexican media reported.

(Reporting by Lizbeth Diaz, writing by Cyntia Barrera Diaz, editing by Jackie Frank)