A 10-year-old child was seriously injured in a crash involving an adult on an electric bicycle in Fadden on Thursday morning.
Police are investigating the collision on a shared pathway near a primary school in the area about 8.45am.
A 46-year-old man was riding the electric bicycle at the time of the accident, police said in a statement on Friday afternoon.
The child cyclist was taken to hospital in Canberra in a serious condition, before being transferred to Sydney for further treatment.
A spokesman said ACT Policing's collision investigation and reconstruction team were investigating the circumstances of the collision.
Anyone who witnessed the accident or had information which could assist police are asked to contact Crime Stoppers on 1800 333 000 or via act.crimestoppers.com.au.