At least 12 people died and 18 were injured last night when hundreds of young party-goers rushed to get out of a crowded nightclub in the Mexican capital during a raid on under-age drinkers, police said.
Nine youths, including several minors, and three police officers were asphyxiated in a scramble to leave the News Divine disco after a tip-off from its owner that police were in the building.
"More than 1,000 people left in a stampede ... for the emergency exit. The exit is very small ... and that's why people were asphyxiated," Mexico City police chief Joel Ortega told the Televisa network.
The emergency exit was partly blocked by boxes, he added.
Two other youths, aged 15 and 18, died in hospital.
Mexican media photographs showed three bodies lying in the street outside the entrance to the nightclub, their shirts and shoes torn off, while dozens of other shoes were scattered about the nearby sidewalk.
Police arrested more than 30 youths and the nightclub's owner.
Mr Ortega said the crackdown on the party to celebrate the end of the school year was not a surprise raid and the owner had been told about the operation.
Selling alcohol to people under 18 is illegal in Mexico and nightclubs are only allowed to operate within certain time limits. However, those laws are largely ignored by bar and nightclub owners.