The mother and grandmother of two toddlers have been arrested after the kids were discovered alone in a Quebec City residence police described as unsanitary.

Neighbours called police on Monday after they saw two two-year-olds alone in the home and were worried they would fall out of an open third-floor window.

Quebec City police spokesman David Poitras said when officers arrived they discovered the kids were locked inside a room with no adults in the home.

"The window screen was on the floor," Poitras told Cogeco Nouvelles. "The children were on the window frame and there was nothing holding them back (from falling)."

Police also noted the home was unsanitary, he said.

"There was waste and feces inside the house, and there was nothing to eat inside the fridge," Poitras said.

The women, 18 and 38 years old, were located by police and arrested for allegedly abandoning the children, who have since been taken into protective custody.