A former policewoman claims she had "never seen terror like it" while rescuing a child who was moments away from drowning at a Norfolk beauty spot. 

Nicola Mills was enjoying an evening swim at Horstead Mill with her partner when she noticed a young girl, who she estimates to be no more than 12 years old, struggling to stay afloat in the water.

The 54-year-old believes the girl had been playing in shallower water and seemed to lower herself, not realising how deep the water was, before being swept away. 

Nicola Mills used her float as an aid to save a young girl from drowning in the Horstead Mill on SundayNicola Mills used her float as an aid to save a young girl from drowning at Horstead Mill on Sunday (Image: Nicola Mills)

"The look on her face was sheer terror, as a police officer I've seen a lot of anger mixed with terror but nothing like that," she said. "I had never seen terror like that in my 19 years at Norfolk Constabulary.

"Her eyes were all over the place because she was so scared."

Ms Mills, who classes herself as a strong swimmer, struggled to keep afloat during the incident on Sunday while she encouraged the girl to grab on to her float. 

READ MORE: Three teens have lucky escape after being cut off by tide

After two attempts, she swam them both to calmer water and out of the mill in less than two minutes and said her police training instincts kicked in.

"She kept getting sucked under and spat back up where she was gasping for air.

 "She was really struggling and went under for a long time and only came up for a half second."

A similar incident occurred at Horstead Mill in 2019 when four teenage girls saved a man from drowningA similar incident occurred at Horstead Mill in 2019 when four teenage girls saved a man from drowning (Image: Archant)

Similar incidents have occurred at Horstead Mill before and Ms Mills explained that many mills are deceptively dangerous.

"We don't want to stop swimming but we should never take the water for granted.

"In Norfolk we have signs but that doesn't take people away from the water. What we need is to understand it more.

"Even if you think you know a stretch of water, it can change weekly and even daily."

The RNLI advises people to never swim in open water alone and to "acclimatise slowly to avoid cold water shock".

It also advises swimmers to stay within a comfortable depth and "float to live".