"We didn't even hear them in the street," she said. "It wasn't until his mate called out and said 'I need some help', and he did. He was out cold."
The resident, who would not be named, called 111 and tried to keep the boys calm.
"The kids were freaking, they were quite concerned," she said.
The woman arranged for one of them to speak with the operator until the ambulance arrived for the youth, she said.
"He had a big bump on his head.
"We were quite panicked but we didn't want to panic the kids. We see them quite a bit. They're not a problem. It's a nice, quiet street."
Resident Chad Parsons said the teen began bleeding from his nose and there was significant bruising to the side of his head.
Mr Parsons, who is trained in first aid, said he checked his vital signs and they were strong. The blood coming from the nose was not especially concerning "because it wasn't gushing out".
"He had a few scrapes to his face but I didn't think it was that bad," Mr Parsons said of his condition. "If he had been wearing a helmet, he'd be sweet."
A neighbour of the youth said he and his friends often rode scooters and skateboards on their long, shared driveway.
"They are always wearing gear - their helmets and stuff. They are often on their scooters," said the neighbour, who would only be known as Jimmy.
"They are really good kids. They are quiet and don't cause any trouble. His mates come here quite often."
