Police are investigating whether an arson attack on a Melbourne gym frequented by bikies was gang-related.
Emergency services were called to Nitro Gym in Hallam, in southeast Melbourne, about 4.30am on Thursday after a passer-by noticed a glow inside the gym.
Several windows had been smashed and police believe an accelerant was poured inside before it was set alight.
No-one was inside the gym at the time but the fire caused significant damage to the building.
The gym's owner posted an update to members on Instagram, saying: "Unfortunately we have woken up to a fire in the complex, we will be closed until further notice".
An arson chemist was sent to assess the scene on Thursday morning as detectives from Victoria Police's Echo taskforce investigate whether the business was targeted because of its outlaw motorcycle gang member clientele.
Police are also investigating a separate spate of fires in the inner southeastern suburb of Windsor overnight which police believed are linked.
A person ignited items at the side of a property on Peel Street after 9pm, which cased significant damage to the premises, police said.
No-one was inside at the time.
A bin was set alight in a second incident a few houses away on the same street before emergency services were called to a third fire where a Land Rover ute was set alight on Albert Street.
Victoria Police have urged anyone with information or CCTV footage from any of the four fires to contact CrimeStoppers.
