Two children were rushed to hospital in serious condition after falling from a third-storey window onto concrete Saturday afternoon in a northeast Calgary neighbourhood, police and paramedics confirm to CBC News.

A five-year-old boy is in critical condition with suspected head injuries and a two-year-old girl is in serious but stable condition after the fall which happened around 2 p.m. in the Redstone community, EMS spokesperson Stuart Brideaux said.

Brideaux said the boy was unconscious when paramedics arrived. A police spokesperson said the children are cousins.

Paramedics are urging parents and caregivers to make sure kids can't access windows by moving furniture like tables, beds, dressers and chairs a good distance from any windows.

As well, screens are not safety devices, he added.

"If they happen to prevent a fall, that would be considered lucky, they are designed to be pushed out in an emergency," said Brideaux.

"They will not prevent a fall. Screens are designed to keep bugs out, not keep kids in."