The little boy stayed in bed and pulled the covers up over his face.
"There was a bit more yelling and then the dude kicked the [bedroom] door in."
The teen came face to face with the intruder who pointed the gun, "probably a rifle", at him through the doorway.
The teen's first concern was for his brother but he remained hidden.
He said one of the three men had been yelling at his father, and two others confronted his 66-year-old grandmother who had also got out of bed.
One of the offenders tried to kick the father but he blocked the move. However, his mobile phone and other contents were stolen.
The trio searched bedrooms and called the name of the neighbour - Mike Bell - before storming next door.
Police said the offenders had mistaken the first home for Bell's house and the attack, in which Bell was shot several times, was targeted.
Bell, 35, remains in Waikato Hospital with non life-threatening injuries.
Hamilton Police Area Commander Inspector Freda Grace said on Thursday investigations so far had established a group of offenders arrived at the street in the suburb of Nawton, approached a house they believed belonged to Bell and knocked on the door.
"A man who lived at the address opened the door and an altercation occurred.
"He was uninjured but understandably shaken by the event. Police are ensuring he is supported."
Immediately after, the group went next door.
"A number of shots were fired and the 35-year-old man they were targeting was hit inside his address. The group have then fled the scene in vehicles."
A scene examination was over by Friday afternoon and police cordons had been lifted.
Grace said police were working to find the people responsible for the attack and had not identified whether gangs were involved.
"We want to reassure the community that they have no need to be concerned following this incident, this was not a random attack.
"The fact an innocent member of the public was accidentally caught up in this incident is upsetting.
"This kind of behaviour is simply not acceptable and we are determined to find those responsible."
Police were keen to talk to anyone who was in the area around 10:25pm that night who may have witnessed anything suspicious or have information of interest to the investigation.
People can contact Hamilton Police on 07 858 6200 or call Crimestoppers anonymously via 0800 555 111.