MEXICO CITY – Mexico City's Human Rights Commission cited evidence on Sunday that police may have partly blocked the exit at a nightclub where a stampede killed 12 people, including a 13-year-old girl.

Police officers responding to reports of drug and alcohol violations raided the News Devine club Friday evening. Panicked revelers piled up in a deadly crush at the narrow exit in a desperate attempt to escape.

“There are photographs and witness testimony that police were posted at the exit, and that this created a blockage – a sandwich effect is what one of the witnesses called it,” said Emilio Alvarez Icaza, head of the rights commission. “The police formed up along the length of the staircase, which was both the exit and entrance and which was already pretty narrow.”

The city's Public Safety Department said it is looking into the allegations but had no immediate comment.

About 500 young people – more than the club's capacity – had packed the bar to celebrate the end of the school year, according to police.

Three young teens – ages 13, 14 and 16 – were among the nine students and employees who were asphyxiated in the crush. Three police officers also died at the club in Mexico City's Nueva Atzacoalco district.

All public servants directly involved in the raid have been suspended, including the police director who led the action.

Police blamed the nightclub's owner, saying he caused the stampede when he announced to the crowd that officers were there to arrest them.

They also said the club was overcrowded and that the emergency exit was locked and blocked by cases of beer.

The owner, Alfredo Maya, and a club employee were charged on Sunday with corruption of minors for allegedly selling alcohol to underage customers, city prosecutors said. They are also investigating other possible charges related to the deaths.

Juan Carlos Maya, the owner's brother, denied that the emergency exit was blocked by anything other than police.

He said conflicting orders from authorities may have contributed to the tragedy: that employees were told to clear the club, but police then prevented people from leaving.

“They were the ones that caused this whole stampede when people were leaving,” Maya said. “It was police incompetence.”

“A precinct official said 'the club is going to be closed, get the people out,'” said Maya, who works at the club and was present during the raid. “People were going down the stairs peacefully. ... But when (police) saw people starting to leave, they closed the door.”

Alvarez Icaza said witnesses also reported some people were beaten during the raid.

Mayor Marcelo Ebrard said the club shouldn't have been allowed to operate and promised an investigation.

The legal drinking age in Mexico City is 18. Maya said alcohol was served at the club, but not to minors.

Of the 108 people detained as witnesses, most were underage, police said.

Alvarez Icaza said investigations are continuing but added that “we cannot continue to have raids like this.”