Eight Melbourne teenagers have been charged following a violent robbery spree in which a woman was clubbed over the head with a metal pole.

The group allegedly mugged a number of people, stole cars and held up milk bars in the city's northern and western suburbs of Derrimut, Newport, St Albans and Deer Park on Tuesday night and Wednesday afternoon.

During one of the robberies a 67-year-old woman was struck over the head and face with a metal pole, police say.

The group, whose oldest member is 18, was arrested on Thursday morning in two cars, one of which was allegedly stolen during the aggravated burglary in Derrimut.

The 18-year-old will appear in Melbourne Magistrates' Court on Thursday afternoon and seven boys will face a Children's Court at a later time.