Three girls ran away after encountering a man exposing himself in Ilkeston, police have told the Advertiser.
The man, who was shirtless, was exposing himself through his flies while touching himself on the footpath beneath Millership Way.
The incident happened at about 5.45pm on Friday as the girls were walking along the Erewash Canal towpath.
When they saw him they turned and ran away.
One of the girls, aged 13, told her mother what had happened, who then called the police.
The girls described the man as aged between 20 and 40 and bald.
He was about 5ft 9ins tall and of medium build and was wearing black jeans and no top.
Police have reported two other flashing incidents in the last six weeks – the most recent was near Kirk Hallam Community, Technology and Sports College when a man exposed himself to three 13-year-old girls on July 2
Another was near Quarry Hill Road on June 4 when two teenage girls saw a man who was naked apart from his shoes.
Anyone with information is urged to call police on 101.