Police are investigating after three people were found dead Sunday afternoon inside a home on a quiet, residential street.
Police said in a news release that the bodies are that of a middle-aged man, a middle-aged woman and a pre-teen boy.
Police also issued a release saying they are searching for a 13-year-old girl "regarding a serious family matter."
The Medicine Hat News is reporting the girl is the dead couple's daughter.
Police have not released any other details nor have they released the names of the dead. Police have not been available for comment.
Police have not said how the three died or whether there is a motive or suspects.
One neighbour said a young boy went to call on his friend at a home around noon. The boy thought he saw a body through a window and ran home to get his mother, who then called police.
Police say they are treating the deaths as homicides.
Phyllis Gehring, who lives next door to home where the bodies were found, said the family has lived there for about three years.
She said they were quiet and were good neighbours.
"We knew them, but it wasn't like they came over or we went over there. We had no problem with them whatsoever.
"I never heard a harsh word between the mother and father. This is very surprising for me. It's very hard to deal with," Ms. Gehring said.
Yellow police tape surrounded the split-level home, located in an established, middle-class neighbourhood.
A white truck sat in the driveway of the house. Its passenger window had been smashed out.
Police were at the home all day and access to the street was blocked off. They used dogs to search through garbage, gardens and alleys.
Four forensic officers, wearing white, periodically went in and out of the house.