POLICE are hunting for a balaclava-clad man who attacked a woman in a violent robbery at a bus stop in Brisbane's south overnight.

A 19-year-old woman was allegedly threatened with a gun after leaving a bus stop on Forest Lake Boulevard at Forest Lake just after 8pm on Thursday.

A Queensland Police Service spokeswoman said the woman heard footsteps behind her as she walked along Settlers Circuit before being pushed to the ground and told to hand over her mobile phone and the passcode to open it.

Police will allege the unknown offender held what appeared to be a handgun to the woman's head while he passed her phone and wallet to two other accomplices.

The woman wasn't seriously hurt in the attack.

Police are hunting for the trio, who were wearing dark clothing at the time. The main man believed to be involved is described as around 172cm tall and was wearing a black balaclava and black gloves.

Anyone with information or who may have seen anything suspicious in the area around the time is encouraged to come forward and report it to Policelink on 131 444.