San Leandro police are investigating a recent string of robberies in the city involving crowds of juveniles and young adults.
The first incident occurred around 10 p.m. Saturday when police said two juveniles at the Bayfair BART station were confronted by a large group of 10- to 20-year-olds.
Police said someone in the group challenged the victims to a fight and one of the suspects threw a punch, prompting the victims to run away.
Police said the victims got separated during the chase and the suspects caught up to one victim at the Bayfair Mall parking lot, knocked him to the ground and kicked and punched him before taking his cellphone and Nike tennis shoes.
The suspects also chased the second victim, but he was able to find a police officer in the area.
The suspects were never caught, police said.
Police said a second incident occurred around 4 p.m. Monday when two middle school students were walking in the 2100 block of East 14th Street.
Police said three older teenagers approached the boys and tried to take a shopping bag containing Nike shoes that one of the victims was carrying.
When the victim resisted, one of the suspects pulled out a handgun and pistol-whipped the victim, knocking him unconscious.
Police said the suspects then beat up the second victim and also took his Nike shoes and iPhone.
The victim who was struck with the gun was transported to a hospital and received several stitches.
Police said there was another robbery about 40 minutes later in a parking lot two blocks north on East 14th Street.
Witnesses told investigators the victims, who had a 2-year-old child in their vehicle, tried to pull into the parking lot but were blocked by several juveniles at the entrance.
Police said the victims asked the teenagers to move, but several starting yelling obscenities at them and told them to "go around."
Police said the adults got out of the car, leaving the child inside, and confronted the teens.
During the confrontation, another teen began ransacking the passenger side of the car, stealing several items from inside.
Police said another teen then got into the driver's seat, put the car in gear and started to drive away with the child still inside.
The victims pleaded with the teenager to stop because the child was in the car and the teen pulled the car over.
Police said the suspects did steal a computer tablet and an iPhone from the vehicle.
Two of the teenagers involved in the incident were arrested on suspicion of assault with a deadly weapon, carjacking, kidnapping and child endangerment.
Investigators said there is no evidence the three incidents are related or involved the same suspects.
Anyone with information about the cases is asked to call the San Leandro Police Department's criminal investigations division at 510-577-3230 or the department's anonymous tip line at 510-577-3278.