A young Colorado girl was so terrified that monsters would come out at night to hurt her family that a local police officer agreed to search her house.

Four-year-old Sidney Fahrenbruch had trouble relaxing ever since her family moved to their new home in Longmont, just north of Denver.

"I heard sounds when people weren't up," she told news channel FOX31.

It was when the youngster was at a community event with the Longmont Police Department in early July that Sidney met her saviour – Officer David Bonday.

"She met Officer Bonday and asked him if he would come search for monsters in our house," Sidney's mother Megan Fahrenbruch said.

Officer Bonday had never hunted monsters, before but agreed to assist the investigation.

Arriving in full uniform at the Fahrenbruch family's home on Sunday (23 July), he let Sidney borrow his police-issue flashlight as they searched the home.

"She just checked under the couch, but he wanted to make sure there weren't any under the couch cushions," Megan said. "And then they ended up going in the front yard to make sure there was no monster activity in the front yard."

Thankfully, no monsters were found in the hunt – and the officer's actions have allowed Sidney to now rest easy at night.

"It's just amazing the confidence he's given her," Megan said. "We're truly grateful to live in a town where the police officer will pay a kid any attention."

Sidney, who frequently wears a police uniform and wants to become an officer when she grows up, often visits the Longmont Police Department to thank officers for their service.

She said Officer Bonday was now her "best friend".

And she now insists she is no longer scared of monsters, saying she would "punch them in the face" if she ever encountered one.