Police are investigating four robberies and three assaults that happened within four hours of each other in Weston-super-Mare on Saturday afternoon.
Officers said the offences were committed by a small group of young people in the Hutton Moor and Maltlands areas of the town between midday and 4pm, and are appealing for any witnesses to contact them.
DI Julie Mackay said: "Recently there has been a sharp decline in these types of offences in Weston-super-Mare.
"It would be a shame if people became unduly worried about their safety as a result of these recent incidents.
"We are investigating the actions of this group of young people and are determined to identify everyone responsible and ensure they realise the seriousness of their actions."
Police said three young people have already been arrested, interviewed and bailed in connection with the incidents.
Any witnesses, or anyone who saw a group of young people in the area at the time, is asked to call 101.