A Police Derry City and Strabane spokesperson said: “Some of our officers were in the Nelson Drive area earlier on Sunday evening, responding to reports of a number of scramblers and motorbikes being used in Kilfennan Country Park.
“The bike pictured above was involved, and was being ridden by a male.
“This male rode directly at an officer, knocking the officer to the ground.
“Thankfully, a number of residents assisted our colleague and he was able to get to his feet to retrieve and seize the bike.
“The male rider and the other bikes made off.
“We are grateful to the residents who assisted, and would like to thank them for their help.
“We would also like to echo their sentiments. Many of the residents expressed concern that it could easily have been a child or an elderly neighbour knocked down.
“If you can identify the people involved, please make contact with us on 101 and quote the reference number 1208 of 27/9/20.”
Information can also be passed anonymously to Crimestoppers on freephone 0800 555 111.