Four revellers have been left with injuries after an 18th birthday party in Melbourne’s east was gatecrashed.

Police said at least one of the gatecrashers was armed with a knife when they barged into the private event at a home in Ringwood just after midnight on Sunday.

Police said at least one of the gatecrashers was armed with a knife when they barged into the private event. 9News

It’s understood the party was wrapping up about that time but there were still about 35 people there.

Police said a number of fights broke out and multiple people were assaulted.

Four guests were hurt but didn’t need to be taken to hospital and there were no reports of stabbings.

The gatecrashers fled before police arrived, leaving detectives trying to identify them.

They’re also trying to figure out exactly what happened, why and whether any of the people involved knew anyone at the party.

Police said they were continuing to “engage with the people who hosted the party”.