The 17-year-old is reported to have been sat with two friends on Marl Croft at around 8.30pm on Monday when a black Corsa pulled up alongside them.
A person inside the vehicle is then said to have pointed a gas powered type gun at the group which fired a ball bearing - hitting the teenager in the right cheek.
Police are now appealing for members of the public to get in touch if they witnessed the incident or have any information that may help with their investigation.
A spokesman for the police said: "A ball bearing became lodged in the teenager's right cheek after someone fired a gas powered type gun.
"It seems that he was sat on his bike in the street when a black Corsa, which is described as only two or three years old, pulled up.
"The gun, which was pistol sized, fired causing a ball bearing to become lodged in the teenager's cheek."
The teenager is not believed to have been seriously injured in the incident.
Ellen Miller, Victim Support Services Director said: "It can be extremely frightening to experience a violent crime involving a weapon. As well as being injured physically, victims are often very seriously affected emotionally.
"It is common to find it hard to deal with the feeling of being powerless after experiencing such a traumatic incident. We know that crimes like this can also have a strong impact on friends and family.Lancashire Victim Services and NEST Lancashire (young victim's service), run by independent charity Victim Support on behalf of the Police and Crime Commissioner, have specially trained staff and volunteers to help people affected by violent crime."
Anyone with information about the incident is asked to contact police on 101 quoting log number 1418 of March 26.
People struggling in the aftermath of a violent crime can get help via Victim Suport via their free 24/7 Supportline number – 0808 16 89 111 or via the website.