Campbellton Royal Canadian Mounted Police Cpl. Alain Tremblay said police were in the initial stages of the investigation "to determine if any criminal act is responsible for the death of the two boys," the Canadian Broadcasting Corp. reported.
Police said the two boys, ages 5 and 7, were at the apartment above the reptile shop for a sleepover with the shop owner's son. Reptile Ocean owner Jean-Claude Savoie found the two visiting boys dead Monday; his son was unharmed.
Savoie told Global News Monday he thought the boys were sleeping until he turned on the light.
"I thought they were sleeping until I [saw] the hole in the ceiling. I turned the lights on and I [saw] this horrific scene," he said. "[The snake] went through a ventilation system. I don't understand how it did it. It went through the ceiling ... and the snake fell through the living room from the ceiling."
Constable Julie Rogers-Marsh said the preliminary investigation indicates the python escaped its enclosure at the store, entered the ventilation system and then slithered into the upstairs apartment.
"It's believed the two boys were strangled by the snake," she said.
Police have the reptile in their possession.
"This is a tragedy," Deputy Mayor Ian Comeau said. "The city is in shock."
Comeau said Reptile Ocean was licensed and "everything was according to our bylaws" and provincial guidelines, CBC News said.
The nearly 100-pound snake, a personal pet on display in the reptile shop, was 11 1/2 feet to 14 1/2 feet long.