Watch Leah's report on the story
People are being warned to stay away from frozen lakes and rivers this winter, after a dog walker risked her life saving her pet Labrador.
She crashed into icy water trying to help her dog, which had fallen in. Luckily both made it out safely.
But London Fire Brigade's Steve Green advised everyone to stay off ice: "It impossible to determine how safe it is.
"And particularly if a pet goes out, such as dog, on the ice and gets stranded, don't go after it."
Last year four people died after falling through ice.
Steve Green added: "During the daytime, particularly when it warms up, the ice starts to thaw and it becomes thinner.
"The ice is thick around the edges so it can lead you into a false sense of security. The further out you go, the thinner it's likely to get."