It's a parent's worst nightmare, and police say it's happened here in London. 

Police are asking parents to inspect trick-or-treaters Halloween candy after a child found a needle in a chocolate bar in the city's south end.

The child collected the small chocolate bar on Tuesday somewhere in the White Oaks area, which has a high number of kids who attend three area elementary schools.

The child was not injured.

London police are in the early stages of their investigation.

"Please inspect all Halloween candy that your children brought home, and if you find anything suspicious, please contact police," London police said in a news release on Wednesday.

Anyone with information is asked for contact police at (519) 661-5670.