An 18-year-old man has been arrested and charged with assault with a weapon in relation to the death of his work colleague at a factory in East Tamaki.

Police and ambulance staff rushed to the Kerwyn Avenue address at 9pm last night after receiving reports a person was seriously injured.

At 11pm police confirmed a homicide investigation had been launched in relation to the 19-year-old male's death.

Police said they were speaking to a man about the incident and were not seeking anyone else.

Inspector Duncan Hall said witnesses were also being interviewed at the commercial address.

Police remained at the factory this morning as the investigation continued.

The accused was scheduled to appear in Manukau District Court today.

In a statement, police said the two men were colleagues at a labour hire company.

Officers would conduct a scene examination at the factory today, alongside forensic experts from ESR.

Further charges could be laid, the statement said, however police were not seeking anyone else in relation to the death.