"There was one girl who ran up here. Because there was something happening over here [the church] and was like 'can you pray with me'."
The neighbours overheard the woman in her late 20s telling people at St Andrew's Presbyterian Church and a police officer who later arrived to talk to her that there was an argument.
The other partygoers were younger than the couple who lived upstairs, the neighbours said.
After police arrived, about six people from the party were speaking to about six police officers outside the block of flats.
The older woman who lived at the flat had been speaking with police officers on her deck and then later police brought a seat down to the front lawn, which was today hidden by the police blue gazebo.
The neighbours told the Herald nothing was happening so they went back inside and that was when they heard a loud scream.
"We don't know where she was. We just heard this loud scream. 'No, no, no'."
"We only heard her [the older woman] screaming afterwards. When she must have been told [he was dead] because they were upstairs for ages."
The neighbours said they believed the people living downstairs may have been partying with the older couple because they saw several people being taken away by police including a younger guy in handcuffs who came out of the downstairs flat, they said.
Another resident told the Herald there was a party happening at the Te Aroha St flat when he arrived home just after 10pm, but it went quiet shortly after that.
The neighbour only realised something happened when he woke up on Sunday morning to see police officers at the property.
An older couple lived in the top flat, he said, adding: "They kept to themselves."
Police were today still at the scene with two officers on guard and others interviewing next door neighbours.
The man died just before 11pm.
Detective senior sergeant Mark Green said the woman would remain in custody until Monday morning when she would appear in the Hamilton District Court.
Forensic scientist dressed in blue overalls can be seen through the windows examining the property and investigating items on the upstairs deck.
The police investigation is ongoing.