The 16-year-old boy was assaulted by a gang of up to four boys at 7.15pm on Tuesday as he walked along Leigh Road near Havant train station.
He was approached at the junction with Russell Road by the gang, who left the teenager with injuries to his face as a result of the attack.
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Police think a car drove past and then the group ran off, according to a spokesman from Hampshire Constabulary.
He said: ‘The group were wearing black tracksuits and had their tops pulled up over their faces.
‘We believe that a car drove past and caused them to run away.
‘Officers have been conducting a number of enquiries to identify the group and we are now turning to the public for help.
‘Were you in the area the time? Did you see what happened or see the group in the aftermath of the incident? Perhaps you were in the vehicle that drove past? Maybe you have dash cam footage from the area at the time?’
Anyone with information about the incident are asked to call the police on 101 quoting reference number 44210461067.