Four teenage boys have been charged with multiple aggravated carjackings across several suburbs after a man had his BMW stolen at knifepoint in Newport last week.

Police allege a 59-year-old man was in his black BMW at the corner of Farm Street and Home Road about 6.45am on Wednesday when he was confronted by a number of males armed with a knife.

He was allegedly threatened before the assailants fled in his vehicle.

Forty-five minutes later, police arrested a youth in a carpark on the corner of Boardwalk Boulevard and Dunnings Road, Point Cook.

A 17-year-old Braybook boy was arrested in relation to the carjacking.

The stolen BMW was found nearby.

Five hours later, police swooped on a home in Hammond Street, Altona.

They arrested three more boys in connection with the carjacking.

A silver Hyundai sedan nearby was seized by police as evidence.

The Braybrook youth and three 16-year-old Altona North boys have been charged with committing aggravated carjackings and armed robberies in Newport, Altona, Yarraville and Pascoe Vale.

One Altona North boy was bailed and the other boys were remanded to appear at a Children’s Court.