Police are appealing for a young woman who was seen 'distressed and shouting' in Clayton-le-Moors to come forward.
Witnesses saw a woman crouching down next to a car on some derelict land used for parking on Whalley Road at around 7.30pm on Friday, April 3.
Officers said she was described as being distressed and shouting, but when disturbed the woman ran away down a nearby alley way.
She is described as white, around 5ft 6 to 5ft 10 tall, of a medium build with long blonde platted hair that reached around half way down her back and thought to be in her mid-twenties.
She was also wearing a white top, dark trousers or jeans and a black scarf.
DS Ian Procter, of Blackburn CID, said: “We have had and continue to have officers in the area searching for the woman so that we can make sure she is OK and help her if needed.
“There was some blood discovered at the scene and we are concerned that the young woman may have fallen unwell or is in need of some medical attention and was clearly seen in a very distressed state.
“I would urge the young woman to come forward and to stress that you are not in any trouble, we just want to ensure that you are safe and well.”
Anyone with information call Lancashire Police on 101 quoting the log number 1121 of April 3.