A teenage girl suffered bruising after she was kicked in the face in a park.
Police say they are investigating a robbery which occurred in Aycliffe Park in Borehamwood at around 6pm on Friday July 23.
Hertfordshire Constabulary says a girl was with a group of teenagers in the park when she was attacked by members of the group she did not know.
She was kicked in the face and had phone taken from her.
Officers investigating the incident are appealing for witnesses.
PC Abigail Devane, who is investigating, said: "Were you in Aycliffe Park on Friday 23 July and did you see this incident? If so, I would like to hear from you.
"I understand there were dog walkers in the area and other park users who may have witnessed this.
"If you are able to help I can be contacted directly via email at abigail.devane@herts.police.uk."
Alternatively, call 101 or report information online at herts.police.uk/report quoting crime reference 41/56345/21.
Or contact Crimestoppers anonymously on 0800 555 111 or visit crimestoppers-uk.org.
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