MEXICO CITY, Oct. 4 (Xinhua) -- Mexican police found the bodies of ten murdered victims Saturday in the northwestern city of Tijuana which borders the United States, after dozens of people were killed last week amid escalated drug gang clashes.

    Five of the bodies were found Saturday in a small lane between two shopping centers in the eastern part of the city, while another five were discovered in a van which has a U.S. license plate, a police spokesman said.

    Investigators said all the victims had been beaten before being executed, and two of them were beheaded.

    The criminals left a piece of cardboard with retaliation messages on the scene, local media reported.

    More than 60 people were murdered last week in Tijuana in increasing drug trade-related violence, according to the judicial authorities.

    In an interview with local media on Saturday, Rommel Moreno, attorney general of Baja California state, blamed the rampant violence on the escalating conflicts between feuding drug gangs.

    He said more than 420 people have been killed in drug-related violence in Tijuana so far this year.

    Tijuana is one of the most violent cities in Mexico where drug, weapons, and human traffickers as well as kidnapping gangs are held responsible for most of the violent crimes.

    According to local media, at least 3,200 Mexicans have lost lives in violence related to organized crime or drug trafficking.