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Shoes left outside the News Divine club in Mexico City where 12 people died in a stampede Saturday. ((Marco Ugarte/Associated Press))

At least 12 people, including youths and police officers, were trampled to death after police raided a Mexico City nightclub on Friday, according to police.

Three officers and nine youths, three of them minors, were killed, Police Chief Joel Ortega said. At least 13 people were injured.

Police went to the News Divine club in northeastern Mexico City on Friday evening to investigate reports that drugs and alcohol were being sold to minors, Ortega said.

The stampede happened after the club's owner announced to the crowd of about 500, which exceeded the club's capacity, that police were there to arrest them, Ortega told the Televisa network.

Ortega said the young people were there to celebrate the end of the school year and many more were waiting to get in.

The venue had a single entrance plus an emergency exit, which was obstructed by cases of beer, he said.

"Many of the people concentrated at the club's emergency exit, but it was too small and it was there that people died of asphyxia," Ortega said.

With files from the Associated Press