MEXICO CITY – Eleven alleged hit men for a powerful drug cartel were captured Tuesday at two Mexico City mansions stocked with grenades and automatic weapons – a day after Mexican authorities reported nabbing one of the cartel’s reputed leaders.

Police said it was the first time they have found a safe house linked to the cartel in the capital city.

“Yes, the cartel is operating here in Mexico City,” said Edgar Millan, top commander of Mexico’s national federal police, at a news conference following pre-dawn raids on two houses in southern Mexico City. Eight men were arrested in one raid and three in the other.

Millan said the men, whose identities were not released, were part of three cartel “commando” groups that may have been preparing attacks in response to a federal crackdown on drug trafficking.

President Felipe Calderon has sent thousands of soldiers into states throughout Mexico to combat drug gangs battling for territory and for control over corrupt local police forces.

The suspects were lined up in the homes’ spacious living rooms and presented to reporters alongside caches of seized weapons, including 20 fragmentation grenades, automatic weapons, rifles, and materials presumably intended for constructing a drug lab.

Police also found 40 bulletproof vests, eight of which bore the initials FEDA, which Millan said was likely a Spanish acronym for “Arturo’s Special Forces.” Authorities also found an unspecified amount of cash in one of the homes.

Arturo Beltran Leyva is one of five brothers believed to be top lieutenants of the Sinaloa drug cartel, based in the northwestern Mexican state of the same name. A second brother, Alfredo Beltran Leyva, was arrested early Monday in the Sinaloa capital of Culiacan with two suitcases containing $900,000, an assault rifle, a luxury SUV and 11 expensive watches. The U.S. ambassador to Mexico, Tony Garza, praised Monday’s arrest as “a significant victory.”