Trumpets and trombones blast across a rodeo ring where women in miniskirts dance with men in cowboy hats and gold chains. Some fans try to climb onto the stage while others whoop to the deafening music and sing along to an outlaw ballad about one of the most-wanted criminal suspects in North America, an alleged drug kingpin.
"We take care of El Mayo
"Here no one betrays him...
"We stay tough with AK-47s and bazookas at the neck
"Chopping heads off as they come
"We're bloody-thirsty crazy men
"Who like to kill."
At the microphone is Alfredo Rios, whose stage name is "The Komander." He's a singer of Movimiento Alterado _ "Altered Movement" in English _ a new commercial brand of "narcocorrido" ballads that bluntly describe drug violence to the oompah beat of Mexico's norteno music.
The songs are filled with unusually explicit lyrics about decapitations and torture, and praise for one drug gang in particular: the Sinaloa cartel and its bosses, Ismael "El Mayo" Zambada and Joaquin "El Chapo" Guzman.
The increasingly popular music is banned on radio stations in parts of Mexico but is heavily promoted over the Internet. It is the brainchild of twin brothers based in Burbank, California, who have long turned to the Sinaloa cartel for artistic inspiration. They won a Grammy award in 2008 for producing an artist who goes by the name of "El Chapo de Sinaloa."
Omar Valenzuela says the music not only tells of the violent world of the Sinaloa cartel, but has received its blessing at least once, when the producers worried about the group's reaction to a song about Manuel Torres, allegedly a top hit man for Zambada.
"We looked for them and asked for permission," Valenzuela said. "We sent them the song and they told us it was OK to release the song. We were afraid. They told us through their people that we were authorized to release any song. Sometimes people can get offended. We didn't want any problems."
The song since then has been downloaded 5 million times from the company website, Valenzuela said, and the accompanying video, which tells of how much gunmen working for Torres enjoy killing, has been watched more than 13 million times on YouTube.
Rios and Valenzuela deny any direct relationship with any cartel, and say they don't receive any money from the gangs. "I wish they were putting in money to promote (the music)," Valenzuela said with a laugh.
For Jose Manuel Valenzuela, an expert on narcocorridos at Mexico's College of the Northern Border, the success of the Movimiento Alterado's music shows that drug traffickers have become more socially acceptable in many circles.
"The social presence of drug trafficking helps this music circulate, and this is also made easier by the easy access to it through the Internet," said Valenzuela, who is not related to the twins.
The new music was born in Culiacan, capital of the Pacific coast state of Sinaloa. The fact that the bands Valenzuela promotes sing exclusively about the Sinaloa cartel has mostly to do with geography, he said.
"In Culiacan, you can't sing about anyone else because they are from here," he said referring to the Sinaloa cartel. "Singing about the Zetas it's not even something you think about. Someone could complain. Nobody wants any trouble."
The Zetas gang, which had its beginning in the border state of Tamaulipas, across the border from Texas, is fighting the Sinaloa cartel for control of drug traffic routes. The battle has caused many of the roughly 40,000 drug war deaths since Mexican President Felipe Calderon ramped up the military offensive on cartels as he took office in 2006.
Some Movimiento Alterado musicians wear camouflage and bulletproof vests on stage and some have names clearly alluding to the Sinaloa cartel, such as Los Mayitos, referring to Zambada's nickname, or The Buchones, as the new rich who made their fortunes in drug trafficking are called in Sinaloa.
That identification can bring dangers.
Gunmen attacked the car of one of the Movimiento's singers, Gerardo Ortiz, in March in the western state of Colima. He survived but his representative and driver were killed.
Valenzuela said the violent lyrics merely describe the times.
The narcos "are cutting heads, and they are more bloodthirsty," he said. "It's in the news every day. If (the ballads) didn't speak about that, they would sound false. If a ballad doesn't express today's language it sounds old."
That's not a new phenomenon: Popular singers from early English troubadours to American gangsta rappers have treated violent outlaws sympathetically.
Movimiento Alterado's boom began in 2009 when the Valenzuela brothers recorded songs by two bands and released them on the Internet because radio stations wouldn't play them. In the states of Sinaloa and Baja California, it's illegal to play songs that advocate drug trafficking on the radio. In May, Sinaloa state Gov. Mario Lopez Valdez went further and banned them at bars and public places. In Chihuahua state, radio stations agreed not to play them.
But on the Internet, the songs are downloaded by the tens of thousands and Movimiento Alterado bands fill dirt-floor rodeo rings and swanky auditoriums across Mexico and the United States.
"The biggest market for this music is in Los Angeles because there we still sell CDs," Valenzuela said.
They also have greater media exposure there. The bilingual Mun2 cable channel of NBCUniversal Inc. ran a reality series, Los Twiins, about the brothers last year. It showed them developing new artists, such as Rios, and featured a guest appearance by Snoop Dogg.
Most of the albums are recorded in Los Angeles at Twiins Enterprises studios, though the Valenzuelas say some are recorded in Culiacan.
Back at the rodeo ring in Naucalpan, on the northwest edge of Mexico City, it was 3 a.m. and the crowd was getting impatient waiting for the star of the night. Finally, the MC announced "the king of the Movimiento Alterado."
Dressed in a black shirt and black pants, Rios looked the part of a pop singer. He invited the audience "to drink solid." The women cheered, and men offered him a drink from their whiskey bottles. The music went on until close to dawn.
Rios doesn't sing about drug traffickers. He sings as if he is one.
"Honestly, I don't like guns, in the first place because I'm not very good at using them," he said. "What I like is playing a role, like in a video game called 'The Executioner.' I play the executioner."