Three of the same group were also charged over an armed hold-up at a Wanniassa service station on Thursday - less than 24 hours earlier.

Two 14-year-old boys and a 15-year-old girl faced the ACT Children's Court on Friday afternoon on charges of aggravated robbery.

A 12-year-old boy avoided a court appearance and was released into the custody of his parents with a court summons.

A police informant told the court the three boys, armed with knives, had entered the Wanniassa 7-Eleven service station with their faces covered and wearing white gloves on Thursday morning.

The trio allegedly threatened a staff member, who handed over about $175, cigarettes and chocolate. The court heard the group then hid the knives and went to a nearby house.

The boys allegedly discussed the success of the hold-up and bought shoes at Westfield Woden shopping centre.

The informant said four members of the group robbed the Mawson service station at knife-point about 1am on Friday.

They allegedly took a box of chocolates and a box of doughnuts before heading to the Woden bus interchange, where they were arrested a short time later.

Magistrate Karen Fryar granted bail to the 14-year-old boy and the 15-year-old girl. The other 14-year-old boy did not apply for release.

All three will reappear in court next month.

Correction: This article initially said the matter was before Chief Magistrate Lorraine Walker.