Riverside Towers in Minneapolis. A 15-month-old toddler fell from an 11-storey balcony in the apartment complex on Wednesday and remains in critical condition. (Wikimedia Commons)

A 15-month-old boy described by doctors as a "miracle baby" was in critical condition at a Minneapolis hospital on Wednesday after surviving an 11-storey fall from the balcony of an apartment building.

Musa Dayib slipped through slits in the balcony railing and landed on a patch of mulch on Sunday, his family told reporters. He was rushed to Hennepin County Medical Center, a pediatric Level 1 trauma centre.

The boy suffered a concussion and fractures to his arms, ribs and spine. He also has a punctured lung, said Christine Hill, a spokeswoman for the hospital.

Dr. Tina Slusher, who is treating the boy, said he avoided any major head injury, and she has never before seen a child survive such a plunge.

"That's a gift from God to the family, because he shouldn't have made it," she told television broadcaster WCCO.