DETECTIVES are warning people to be on their guard while out walking in the dark after an 18-year-old woman was indecently assaulted in Petersfield last week. The victim was walking along Pulens Lane at around 6 pm last Thursday when she was approached by a man who got out of a small white van with the sign "R+B" written on it. The man grabbed the victim and exposed himself to her while making sexual suggestions. The girl then ran away. The man police want to speak to is described as white, aged around 19, with a skinny build and short, gelled, brown hair. He was wearing jeans, trainers and a blue shirt. Detective constable Claire Hodgson said part of the incident was witnessed by a taxi driver in a dark red vehicle. She said: "The taxi driver shouted at the man to leave the girl alone and appeared to wait until the victim had run away from the offender. "We are extremely keen to speak to the driver of this vehicle as he may have vital information to assist us with this investigation. "I would also appeal to anyone else who was in the area at the time of the incident to come forward. "The letters 'R' and 'B' on the side of the van were written in black and the plus sign was white, enclosed in a blue box. "It is possible that someone saw this van being driven around the area. If you have any information that you believe may help our enquiries, please get in touch at the earliest opportunity. "I would like to remind members of the community to be vigilant when out walking in the dark.  "Try to stick to bright, well-lit and busy areas, be aware of who is around you, and look confident." Anyone with any information regarding this incident should contact Det Con Hodgson at Alton CID on 0845 0454545, or call Crimestoppers anonymously on 0800 555111.