There's concern serious violent incidents on public transport could be on the rise.

An aggravated robbery happened on a Lower Hutt bus on Friday, allegedly the result of a mass brawl between 15 young people.

Six people were taken into custody and one passenger had minor injuries.

Public Transport Users Association Coordinator Jon Reeves told Tim Dower it's a big problem.

He says potentially the gravity of the situations is getting worse and that he would hate to see copycat type incidents.

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