Hong Kong  - Hong Kong police on Wednesday were investigating a school brawl involving 50 students after a video of the melee was uploaded onto the YouTube website.

Tens of thousands of people have viewed the 2.5-minute clip, which shows two groups of teenage students attacking each other on the grounds of a housing estate in the city.

The video appears to have been filmed from the window of a high- rise apartment block overlooking the scene of the brawl, which took place Monday in the inner-city Ho Man Tin district.

A police spokesman said that detectives were studying the footage and speaking to schools whose students they believe may have been involved. No one had so far been arrested, the spokesman said.

Officers are investigating whether triad gangs, secret societies which recruit in Hong Kong schools, were involved in the incident.

In the past, police have been called in over brawls that have been filmed inside Hong Kong schools with students' mobile phone cameras and uploaded onto popular websites. (dpa)