Honolulu police homicide detectives are investigating the death of a man Sunday morning in Makiki and have in custody two men, ages 26 and 18, on suspicion of murder.

The Honolulu Medical Examiner has yet to make positive identification of the man who died. Police say he was 30 years old.

The 26-year-old man has a Kauai address. The 18-year-old has a Palolo address.

Witnesses and relatives of the 18-year-old man say the victim was the aggressor and that the men police have labeled as suspects were trying to stop him from stabbing the victim’s pregnant girlfriend. After the stabbing, they said, they saw the girlfriend bleeding from a wound to her hand that was caused by her grabbing the knife blade.

Police say they were sent to a Metcalf Street home with witnesses attempting to restrain a suspect. When the officers arrived, they found the victim unresponsive and immediately began efforts to keep him alive until a city ambulance arrived.

The ambulance service said one of its crew took the man in critical condition to an area hospital, where he later died.

The home where the incident happened shares a driveway with other homes at 1906 Metcalf St.

Police said there was a struggle in the house, people intervened to assist and that during the struggle the victim became unresponsive. They said there are conflicting reports on whether the victim lived at the Metcalf Street home.

Neighbors said the man’s girlfriend lives in the home and that they often saw the man there.

They said they were awakened early Sunday by the girlfriend’s sister, who ran over to their home yelling for help.

One witness said when she entered the home, she saw the 30-year-old man on top of his girlfriend holding a knife above his head. She said the girlfriend’s brother-in-law, the 26-year-old, was struggling with the man, trying to prevent him from stabbing the girlfriend.

Relatives said the 18-year-old man, who was spending the night with them, also answered the call for help and struggled with the 30-year-old. They said he didn’t even know the victim.

Had he not helped, they said, the man’s girlfriend, her sister, the sister’s husband and child, who were in the home Sunday morning, all could have died.

The relatives said the teen just graduated from high school and is always helping people. But they say this incident might make him think twice about offering to help someone in need.

CORRECTION:  The man who died Sunday in Makiki was not stabbed. An earlier version of this story and the story in the print edition said he was stabbing victim.