Police officials on Tuesday fired 17 officers here in connection with a botched raid on a bar last week that triggered a stampede, leaving a dozen people dead.
The firings came as newly released video footage showed police officers blocking exits as hundreds of young patrons tried to flee. The bar's owners were suspected of serving alcohol to minors.
The incident, at a bar called News Divine in a gritty section of northern Mexico City, has been the talk of the capital for days and spurred a flurry of finger-pointing.
Family members of those who died have gathered in front of the bar to demand punishment for police and borough officials involved in the raid. The dead included a 13-year-old girl.
Some politicians have called upon Police Chief Joel Ortega to resign. But he has remained, promising to punish any officers found to have erred or acted improperly.
The city's popular left-wing mayor, Marcelo Ebrard, denounced the raid in harsh language, vowing a thorough investigation and swift corrective measures. The incident represents the first serious political crisis for Ebrard since he was elected mayor in 2006.
The dead consisted of nine patrons and three of the officers who took part in the operation, which authorities said was sparked by complaints that minors were being served alcohol. Police arrested the owner, Alfonso Maya Ortiz.
The legal drinking age in Mexico is 18.
Hundreds of young revelers, many of them celebrating the end of the school year, were packed inside the 1,100-square-foot bar by the time police arrived late Friday afternoon.
The owner announced the raid over a loudspeaker and asked everyone to leave, promising free entrance the following week. But witnesses said they quickly found themselves trapped amid stifling heat.
"The police told us they were not going to let us leave and closed the doors," 16-year-old Rebeca Mohzo told the Televisa network. "Everyone was desperate because there was no air."
Police videotape of the scene showed pandemonium as patrons were pressed against the exits, many screeching in fear. They were shown fanning themselves in the heat and could be heard pounding on the locked doors.
The footage, broadcast repeatedly Tuesday on television, also showed a tumultuous scene outside the bar as police attempted to revive those who had collapsed, including an officer.
Separate footage, apparently shot by an onlooker and posted on YouTube, showed helmeted police using their shields to strike some of the escaping patrons.
Mexican media reported that prosecutors were considering charges against the commander in charge of the operation, Guillermo Zayas. He was fired immediately after the raid.
Among the 17 officers fired was one who had been honored previously as officer of the year.
The bar's neighbors said they had complained repeatedly about suspected underage drinking and possible drug use. The top official for the Gustavo A. Madero borough said Tuesday that an inspection of the bar in August had found several code violations but no evidence of alcohol being served to minors.