Four teenage boys were taken to hospital after being beaten by a gang of youths wielding baseball bats and metal poles in Prenton.
The 16 and 17-year-olds were set upon by around 20 youths in Duck Pond Lane Park, behind the car park of Aldi supermarket on Woodchurch Road on Saturday night.
Police are describing the incident as an unprovoked attack which left all four boys requiring treatment for a series of minor injuries.
The gang, which made off before oficers arrived, are described as between 12 and 20 years of age and wearing dark clothing.
Sergeant Simon Douch from Merseyside Police said: “Although it is early in our investigations, this appears to have been a completely unprovoked attack.
“The incident took place in a public place and I would urge anyone who witnessed it or knows who was involved to do the right thing and call police immediately, whether directly or anonymously through Crimestoppers.
“Although we do not know at this stage exactly how many were in the group, we are keen to speak to anyone who saw a group of youths in and around the area in the early evening, including the park, the Arno gardens, or close to the supermarkets on Woodchurch Road.
“We believe that the youths directly involved in the assault were part of a larger group and I am sure some of these young people would be appalled at the actions of those responsible, and would not want to be associated with such cowardly actions.
“The victims are understandably shocked at what happened and are being supported by their families and police at this time. We are all thankful that these boys were not more seriously injured.
“I would like to reassure people that incidents like this are rare on the Wirral but we will be increasing patrols in the area and will be doing everything possible to bring the offenders to justice.”
Anyone who has information is urged to contact detectives on 0151 777 2265, call 101, or Crimestoppers on 0800 555 111.