VANCOUVER -- A relative has been arrested after a man was killed and a woman injured in what police describe as a "family dispute" that turned deadly.

Mounties were called to a Maple Ridge neighbourood at about 11 p.m. Wednesday following an incident in a home on Nelson Court.

When they arrived, firefighters and paramedics were already on scene.

A man in his 20s was found dead, and a woman was found with what the RCMP described as "significant injuries."

She was taken to hospital for treatment of non-life-threatening injuries.

Another man was arrested at the scene, Mounties said.

The Integrated Homicide Investigation Team has been called to the scene and – while it would not give specifics – said the person in custody is a relative.

IHIT Sgt. Frank Jang said only that the man arrested is also in his 20s, and the woman is older than the deceased victim and the suspect.

"The big question on everyone's mind and on our minds is why. Why did this happen?" Jang said at a news conference.

Officers were seen entering two neighbouring homes and the entire block was behind police tape. A public garbage can nearby was also taped off, but IHIT said it believes the crime scene itself is focused on one home.

Investigators believe that's where the attack happened.

Earlier in the day, a dog team searched the front yards and forensic investigators canvassed the area.

The large police presence alarmed many neighbours who watched the scene unfold from their front porches.

Ridge Meadows RCMP says there is no ongoing threat to the public.

With files from CTV News Vancouver's Sheila Scott