Three men were injured in Perth's CBD when a group of people, including a 13-year-old, attacked them with machetes, reports say.

Nine News Perth has aired phone footage from a spectator to the incident on William Street around 2am on Sunday.

shows people, armed with what appear to be machetes, attacking three men. Credit:9 News Perth

It shows people, armed with what appear to be machetes, attacking three men.

One can be seen bleeding freely from the head.