A Perth teen has been found after losing school group along the Murray River Trail

A 17-year-old Perth teenage girl was separated from her school group on Tuesday during a mountain bike excursion along the Murray River Trail in Nanga Brook.

Yarloop Police said the youngster became separated from a small group of riders at about 1pm and attempts from students and teachers to locate the missing girl were unsuccessful.

Police were notified of her disappearance at 4.30pm, with officers from Yarloop, Dwellingup, Pinjarra and Police Air joining the search.

The teenager was spotted by a police helicopter four hours later which directed ground officers to her location.

Yarloop officer-in-charge Sergeant Wayne Byram said the girl was found in good health but “wet, cold and hungry.”

“She had no injuries but was taken to the Peel Health Campus as a precaution,” he said.

“This was a swift and well coordinated search by all officers involved, which resulted in a great outcome, particularly given the darkness and dreadful weather.”