Eight youths have been arrested after police chased down the suspected stolen van they were driving and burst its tyres following a spate of armed robberies in Melbourne's west.

The HiAce van was spotted by police in Hoppers Crossing at Mossfiel Drive about 10.10pm on Thursday, hours after a pharmacy and bottle shop were held up, police said.

Police punctured the van's tyres with stop sticks at Shaws Road, Werribee.

But the van kept driving and led police on a low-speed pursuit, police said, before it pulled over at Market Road and at least 10 people piled out.

Police swarmed and managed to arrest some of the youths. Seven males and a teenage girl, aged between 14 and 20, were arrested with the help of a dog squad.