Ozgur Ontas, who filmed the rescue, said the men were in the icy water for between 10 and 15 minutes.
“It’s problematic for dog walkers,” he told BBC News.
“It wasn’t just this man, other people’s dogs also went into the lake and ran on the ice. This could happen again.”
Essex Fire and Rescue Service, which responded to the incident, has now warned the public not to enter cold waters to rescue animals.
Gary Dyer, its watch manager, said anyone who did so risked being “overwhelmed” by the low temperatures.
“We completely understand why people want to help in situations like this, but cold water can overwhelm the body very quickly,” he said.
“The safest thing to do is stay out of the water and call us – we have the training and equipment to respond safely.”
A spokesman for the fire and rescue service said: “Firefighters were called to a lake in Rangers Road, near Buckhurst Hill, following a dog rescue attempt that left two people in icy water. A member of the public fell through ice in an attempt to rescue a dog.
A passer-by then entered the water to try to help. Both people were able to get out of the water and were left in the care of the ambulance service. The dog was safely reunited with its owners.”
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