A brave passerby risked hypothermia as he jumped into the ice-cold waters of a frozen lake to save a little boy from drowning.

The heroic resident leaped into the freezing water in Lanpo Lake, located in the city of Kuancheng, in Jilin Province, north-eastern China, on November 26.

Witness Mr. Zhao, who recorded the rescue, said the boy was playing on the frozen surface of the lake when he accidentally slipped and fell through the ice.

Without a second's thought, a man who stood nearby immediately jumped in to save the child from drowning.

With the help of an inflatable raft that someone had apparently used as a sleigh, he managed to quickly get the boy out of the freezing water and then pushed him onto the solid ice.

A bystander then helped the man get out with an old broom. He came out of the water completely soaked.

He threw a winter jacket over his shoulders and quietly left while trying to shake water off his phone which he had not even taken out of his pocket before jumping in after the boy.

Other people present rushed the boy home to his parents, who reportedly expressed deep gratitude to his saviours.

The rescuer's identity remains unclear, although some social media users recognised him as a veteran soldier surnamed Yu.