Ten teenagers have been arrested in relation to a series of armed robberies and aggravated burglaries across Melbourne and Geelong.

During one of the armed robberies a 67-year-old woman was struck over the head with a metal pole several times, said Sergeant Cameron Scott of Victoria Police. "She received facial injuries and was taken to hospital."

CCTV footage shows one of the alleged thieves at a St Albans milk bar. Credit:Channel Seven

That armed robbery was one in a rapidfire series of alleged crimes in four hours from midnight on Tuesday through Melbourne's western and north-western suburbs. Eight teenagers have been charged after alleged aggravated burglaries, armed robberies and attempted armed robberies of milk bars in Derrimut, Newport, St Albans and Deer Park.

The males charged are aged between 16 and 18. When arrested on Thursday morning the group were in two cars, one of which was allegedly stolen during one of the raids. CCTV footage from one of the milk bars allegedly shows the youths storm in with their faces obscured. They begin aggressively smashing the glass counters with weapons, including a hammer.