Young people in Poole, Dorset, have been warned to be vigilant after three reports of sexual assaults on young girls in recent weeks.
Dorset Police said since mid-September three girls, all aged 15, had reported being attacked in Talbot Woods, Rossmore and Alderney.
Officers said there is no clear evidence the incidents are linked.
Police have issued descriptions of two of the attackers and are appealing for witnesses.
On 20 September 2010, police received a report that a 15-year-old girl had been sexually assaulted in Talbot Woods at about 1500 BST on Wednesday, 15 September 2010.
Another girl, aged 15, was sexually assaulted along Northmere Drive in Rossmore, at about 2000 BST on Sunday, 26 September 2010.
A third 15-year-old girl was sexually assaulted on the Bourne Valley Reserve, near Monkton Crescent in Rossmore at 1730 BST on Friday, 29 October 2010.
Inspector Adrian King, of Dorset Police, said: "I would advise young people in the area to be conscious of their own personal safety, particularly in secluded areas."
The suspect being sought in connection with the second assault is described as in his late 40s or early 50s, 6ft tall, of skinny build with medium length dark greying hair and a crooked nose.
He was wearing black shoes, black trousers and a short black jacket, possibly quilted or fleecy, with a light-coloured hooded top underneath.
The person responsible for the third attack is described as white, about 5ft 9ins tall and of large build.
At the time of the incident, he was wearing a black zip-up hooded top, black tracksuit bottoms and he had a dark-coloured scarf covering his face.