PARIS (AP) -- A French police official promises to "go all-out" to try to stop the spread of a copycat crime called "happy slapping."

Several European countries have seen a growth in assaults in which accomplices record the attack on a cell phone camera and then trade the images.

The fad started in Britain.

French police say they know of about 20 cases of filmed violence.

A French paper reports in one of the cases a young girl was gang-raped and pictures circulated at her school.

In another case, a student pummels a teacher and wrestles her to the ground.

A police captain in Paris says some young people see the exhibitions "as a way for the poor to get revenge against the rich."