A post on the Bishopdale Community Group on Facebook on Monday from someone who had their radar detector stolen attracted more than 50 comments.
"Keep an eye out for this person and silver BMW. Scouted our small cul de sac in Nunweek Park at 4.57 last night and returned to smash our car window at 6pm to take a radar detector (sic).
"The car was up our drive and it was completely brazen at this time of the day," the post said.
More people then came forward about similar experiences in the city recently.
"These same guys smashed the window of my car and took my radar around 6pm in Rolleston on Sunday.
"There were two of them in the car, one bigger and one smaller with a child in the back. They seems to be all around Christchurch. Low life's just causing grief for way too many people (sic)."
Another commenter said the same thing happened to them last Friday in Belfast.
Police are investigating the incidents.