Moscow: Search crews have pulled more bodies from a huge pile of rubble at a collapsed Russian apartment building, bringing the known death toll to 21.

The bodies found on Wednesday in the city of Magnitogorsk included a 3-year-old girl, Russian news agencies cited the emergencies ministry as saying, reports the UNB.

An 11-month-old boy who was pulled alive from the wreckage on Tuesday, nearly 36 hours after the building collapsed, was in serious but stable condition in a children's hospital in Moscow. He was flown about 1,400 kilometers (870 miles) to the capital in a plane dispatched by the Health Ministry.

Health Minister Veronika Skvortsova said Wednesday that the boy suffered superficial head wounds but no apparent brain damage.

Authorities said 20 people who lived in the building remain unaccounted for, including five children.

But the prospects of finding any of them alive in the rubble appeared dim after two frigid nights in which temperatures fell to about minus 20 degrees Celsius (minus 4 degrees Fahrenheit). However, a cat was pulled alive from the wreckage on Wednesday afternoon, about 60 hours after a section of the 10-story building collapsed.

The Monday pre-dawn disaster came after an explosion that officials say was likely caused by a gas leak.

A day of mourning was declared in the Chelyabinsk region that includes Magnitogorsk, and residents laid flowers and place candles at the scene. Some Muscovites laid commemorative flowers at the entrance of the office for the regional government's representative in the capital.