The 20-year-old man will appear in Melbourne Magistrates Court on Wednesday afternoon following a spate of alleged crimes across Frankston, Carrum Downs, Moorabbin and Seaford.

He is accused of the attempted kidnapping of the girl at a Frankston bus stop about 7.30am Tuesday.

It also follows an incident in Carrum Downs where a firearm was used to threaten two people in a car, and another incident at a Moorabbin shopping centre where the man ran off from security.

Detectives arrested the man on Wednesday morning at a Carrum Downs property.

He faces 20 charges including attempted kidnapping, attempted child stealing, unlawful assault, theft of motor vehicle, possess controlled weapon, possess imitation firearm, affray, careless driving, criminal damage, possessing a drug of dependence.

Detectives continue to appeal for a man driving a blue sedan who stepped in to assist a young woman during the alleged kidnapping in Frankston, to come forward, along with any other witnesses.

Australian Associated Press