Two children aged five and seven were killed after a giant python escaped from a pet store and strangled them to death while they were asleep.

The tragic incident took place in New Brunswick city of Campbellton, Canada when the brothers Connor and Noah Barth were sleeping in their room.

The 16-foot African Rock Python, which lived in a pet store below their apartment, escaped from its cage and slid upstairs inside the boy's room through the ventilation ducts and crept onto the ceiling.

The boys had come to stay for the night with Jean-Claude Savoie, owner of the Reptile Ocean pet store which houses exotic animals, including crocodiles and tarantulas. The children belonged to Savoie's best friend Mandy Trecartin.

According to Savoie, he went into the children's room at about 6.30am on Monday, only to find them dead. He found the snake coiled in a nearby hole.

Savoie believes the snake fell on the boys while creeping on the ceiling and then attacked them.

"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," he added.

According to The National Post, the snake was 'vicious' and rarely handled.

"The kids were always playing and laughing. They were really full of joy and lots of energy," neighbour Diane Fournier told Mail Online.

She also added that she often saw the children play and that they were fascinated with the animals in the store.

Fournier further said that that Savoie's pet shop also functioned as a zoo with numerous school children and groups going there to visit the animals.

Savoie said he was clueless how the python, he owned for more than ten years, escaped its cage.

The cause of the children's death would be confirmed after an autopsy on Tuesday.

Meanwhile, the python is being examined by the Royal Canadian Mounted Police (RCMP).

New Brunswick RCMP spokeswoman said it is examining if any charges against the pet shop owner in connection to the children's death needs to be laid.