The teenager appeared via audio-visual link in the ACT Children's Court on Monday, having allegedly been behind the wheel of a Toyota sedan when it crashed into a tree in the northbound lanes of the Monaro Highway at Hume on Sunday morning.

Two teenage girls, aged 14 and 15, were found in the vehicle and declared dead at the scene.

Police said two other teenagers were thought to have been involved and to have fled the scene.

After subsequently being found, they received medical attention.

The boy alleged to have been behind the wheel has also been charged with single counts of driving as an unaccompanied learner, and failing to stop and render assistance.

Police allege he was in breach of bail and a good behaviour order.

A Legal Aid duty lawyer did not apply on Monday for the boy to be granted bail, and magistrate Jane Campbell adjourned the matter until October 31.

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Previously, police said officers were called to the scene of the crash about 8am on Sunday, when they found the girls dead in the car.

It is unclear, however, exactly when the crash happened.

The two teenage passengers were thought to have died some time before police and ambulance crews arrived at the scene.

Detective Acting Inspector Brian Tadic said the impact was "severe".

The northbound lane of the Monaro Highway was closed for most of Sunday.

The crash takes the number of road deaths in the ACT this year to 14, compared with 11 for all of last year.

Police have asked anyone who might have information about the crash to contact them.

"Anyone who witnessed the car leave the road or who drove past the collision site and saw the vehicle prior to 8am on Sunday is urged to contact Crime Stoppers on 1800 333 000, or via the Crime Stoppers ACT website. Please quote P2107669," a police statement said.

"ACT Policing urges all road users to slow down and drive to the conditions."

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