Homicide detectives are investigating after a 17-year-old boy died in hospital after he was allegedly attacked at a stadium in Werribee last night.

The teenager, from Wyndham Vale in Melbourne's west, was taken to hospital after he sustained life-threatening injuries just before 6:00pm.

Basketball games at Eagle Stadium in Werribee were called off as forensic police gathered evidence at the scene.

A 15-year-old boy was arrested and questioned by police, but he has since been released as the investigation continues.

Detectives are appealing for witnesses to come forward with any information.