A flasher indecently exposed himself in Anfield.
A woman reported she had witnessed the man performing a sex act shortly after 11.30am on Friday, while she was in Stanley Park, near the lake, with two other women.
The man made off on foot in the direction of Anfield Road.
Patrols attended and searched the area but the man was not found.
He is described as white, in his 30s, with dark blonde hair of medium build, wearing a dark t-shirt and dark shorts and white underwear.
Detective Inspector Sean Kelly-Marland said: "We would like to appeal to the public who may have witnessed a man fitting this description in and around the Stanley Road area to come forward with any information that they might have as it could be vital to our investigation.
"I would like to stress that these kinds of incidents are rare and unusual and I would like to reassure the local community that we are taking this matter very seriously."
An investigation into the incident is ongoing.
Following the incident, many women took to social media to say they had either witnessed or been the victim of flashing incidents in the Anfield area.
Anyone with information is asked to contact Merseyside Police social media desk via twitter @MerPolCC or Facebook Merseyside Police CC. You can also call 101 quoting incident reference 0415 of 11/9/19 or contact the independent charity Crimestoppers anonymously, on 0800 555 111 or via their online form here.
