MEXICO CITY – Two headless bodies are dumped on a street in suburban Mexico City along with a message sent by a mysterious group called "The Hand with Eyes." Days later, a severed head shows up in a car abandoned outside an elementary school in the same suburb.

For drug lords, this sprawling metropolis of 20 million has been a favorite hide-out and place to launder money, making Mexico City somewhat of an oasis from the brutal cartel violence along the border and in outlying states.

Now a spate of killings and decapitations never before seen have authorities batting down fears that a once-distant drug war is making its way into the capital. Instead, they say, the violence since late last year comes from street gangs fighting for an increasingly lucrative local drug market.

While drug use in Mexico City doesn't come close to that in the U.S., it has grown dramatically in the past decade. About 8 percent of middle and high school students here now experiment with drugs, said city drug addiction adviser Patricia Reyes, a number that has climbed from 2.5 percent in 1998 according to national surveys.

Some of the high-profile violence comes from groups that are remnants of the Beltran Leyva cartel, which has splintered and moved closer to the city since the Mexican navy killed leader Arturo Beltran Leyva in December 2009. Others imitate cartel tactics to gain turf.

"I think of these groups as cells, as franchises," said Alfredo Castillo, attorney general for Mexico state, the suburban area surrounding Mexico City. "As franchises what do they want? They want the know-how, the business model, and in the end, they want their backing in case of an extraordinary problem."

The mass killings started late last year, when a drive-by shooting in the rough neighborhood of Tepito killed six youths and a family of five was slain in a drug-related attack in the south of the city.

The violence intensified earlier this year as Juan Vasconcelos, a reputed local gang assassin, allegedly went on a cocaine- and alcohol-fueled killing spree that ended with his arrest in February.