The Allegheny County medical examiner has determined causes of death for 3-year-old twins who perished in a North Braddock house fire Friday.

One of the boys died of burns and smoke inhalation and the other died of smoke inhalation and carbon monoxide poisoning, the examiner ruled. The office still is working on identifying the children.

The manner of death -- whether they were accidents or homicides -- was listed as pending. Allegheny County detectives were investigating.

The fire, near the intersection of Rebecca Avenue and 13th Street, was first reported about 3:30 p.m. when a passerby spotted smoke and called 911.

Family members identified the twins as Ky'heir and Dy-hier Arthur and said they heard that the boys' mother left them unattended for a few moments while she went to find another child.

When firefighters arrived, the home was fully engulfed in flames.

Firefighters found one of the boys on the first floor of the home, where investigators suspect the blaze began. The other child was found on the second floor.

No cause of the fire has been released.

First Published: January 6, 2013, 6:00 p.m.