A 13-year-old boy was held at knifepoint as three men made off with his bike in a "frightening" robbery.
The schoolboy was walking with friends near the canal bridge, close to Sefton Street in Litherland, towards Tesco before he was set upon by the group.
Police said the boy was threatened with a knife and his bike was stolen, before the men made off.
Detective Chief Inspector Gayle Rooney said: "This was a frightening experience for a group of teenagers to go through, and we're determined to find those responsible and put them before the courts."
The bike has been described as a black GT Aggressor Sport, with white writing.
Officers are appealing for further information to the incident and said CCTV enquiries re ongoing.
The victim is also being supported by officers.
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DCI Rooney said: “If you were in the area around 7.30pm and saw or captured anything, let us know and we will take action. Our enquiries are ongoing, and we’d like to hear from anyone who has a descriptions of the men involved in this cowardly offence.
“Likewise, if you have seen this bike in the area or been offered it for sale, come forward."
Merseyside Police added: "Please contact us via our social media desk on Twitter @MerPolCC or Facebook ‘Merseyside Police Contact Centre’ with reference 21000116553.
"You can also contact the independent charity Crimestoppers anonymously, on 0800 555 111 or via their online form at: https://crimestoppers-uk.org/give-information/give-information."