Hamilton police have arrested three teenagers after several women were robbed at gunpoint in Ancaster and Hamilton.

Two youth boys and an 18-year-old man are facing numerous robbery and firearm charges in connection with four incidents, including two in the same plaza just days apart.

Around 1:30 p.m. Monday, police say a woman in her seventies got into her vehicle in the Pet Smart parking lot at the Meadowlands Power Centre in Ancaster.

A young man got into the back seat of her car and the victim jumped out and screamed for help. Bystanders came to her aid and the man ran away through the parking lot on foot.

Police say two other similar incidents happened on Monday. Another elderly woman had a gun pointed at the back of her head after she got into her vehicle in the Lime Ridge Mall parking lot. The man, who was sitting in the back seat of her vehicle, stole her purse and fled the area on foot.

Around 8:30 p.m., a woman was walking home from Mohawk College when, police say, she felt something on her neck. When she turned around she says a male was pointing a handgun at her and stole her wallet and cell phone. The suspect started to get into a waiting black vehicle but the vehicle drove off before he could do so and he fled on foot.

Last week, a woman in her eighties got into her vehicle in the Best Buy parking lot in Ancaster and found a young man sitting in her back seat. The man immediately pointed a gun into her side and told the woman to drive him around.

At one point, investigators say the suspect forced the woman into the passenger seat and drove her around while keeping the gun pointed in her direction. He also forced the victim to drive to an ATM machine and withdrawal cash.

Two suspects, aged 15 and 18, are facing robbery and firearm charges. In addition to robbery and firearm charges, the 16-year-old man is also charged with kidnapping, threaten death, and use stolen credit card.

Police seized stolen property and an imitation pellet pistol they believe was used during the robberies.