Neighbours who were at the scene of a deadly shooting in Christchurch say there was a party, and they heard shouting and swearing after the gun shots.

Police have launched a homicide investigation after a 16-year-old was found dead at a house in the suburb of Casebrook.

Detective Inspector Michael Ford said police were called to a firearms incident at the property just after 11pm.

When they arrived they found the boy was dead.

A homicide investigation, including a scene examination, is under way to determine what happened and who is responsible, he said in a statement.

Armed police remained at the scene through the morning, and a vehicle of interest has been identified.

RNZ understands the shooting happened at a party in Heaphy Place.

A neighbour said it was a normal sized gathering, and she initially thought fireworks had been set off.

She said the party went silent shortly after police arrived, and she heard shouting and swearing.

City councillor Andrew Keown said it's sad to see another teenage homicide connected to a party, after a 16-year-old was stabbed in the city in August.

He said he came across the scene at about 11.30pm on his way home, and officers had cordoned off a section of Cavendish Road.

"At the intersection the roads were blocked, there were police standing there with assault rifles on duty and then I saw them pulling up the police emergency rig which normally means that there's a crime scene that they are securing.

"There were several police cars at the Northcote Road end and a couple at the other end as well."

Detective Inspector Ford said police are asking anyone who was in the area at the time, and who can assist with their inquiries, to contact them.

Anyone with information can ring police on 105 and quote event number P048523046 .

Information can also be provided anonymously via Crime Stoppers on 0800 555 111.