Ali Sari, 18, one of the suspects believed to be behind a crime spree across Melbourne. Credit:Victoria Police

Three teenagers wanted over a violent two-night home invasion and car theft spree have been in custody before and have shown no signs of slowing down, police say.

Police Commander Stuart Bateson told radio station 3AW that detectives had spoken to the teenagers' families and have asked them for help catching the suspected offenders.

The youths allegedly smashed their way into homes in Mernda, Bentleigh East and Derrimut, threatened and assaulted residents, and carjacked a young mother in a city-wide rampage that began on Sunday night and continued into Tuesday morning.

One of the alleged offenders was arrested on Tuesday but three others are still on the run.