A 13-year-old girl was allegedly assaulted by two teenage girls as she got off a bus in Erindale early on Friday afternoon.

Police say the 13-year old suffered significant injuries from this assault, including having her braces dislodged.

Then, about 3.20pm on Saturday police responded to reports of several more incidents within the Tuggeranong Town Centre allegedly involving the same two teenage girls as well as other juveniles.

These include the alleged assault of an elderly man and staff in Big W, and the alleged assault of another 13-year-old girl at the Tuggeranong bus interchange, who also suffered significant injuries, including spinal fractures.

The two girls were arrested nearby a short time later  and have been charged with joint commission assault occasioning actual bodily harm.

There may have been other incidents involving this group around the same time and police are looking for any victims and witnesses.

Call 1800 333000 or via the Crime Stoppers ACT website.