AGOURA HILLS (CBSLA.com) — “I was startled and woke up to somebody ringing my doorbell and beating on the door.”

It was just before 1 a.m. when Bruce Grant was jarred out of bed at his Agoura Hills home.

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“At that moment, the window started banging to the right, in my living room. So, I ripped over there, thinking that somebody was going to break the window trying to get my attention. I opened up the curtains and saw a full-grown person in a monkey suit, within a foot of my face.”

(credit: CBS)

(credit: CBS)

The man in the costume wasn’t alone.

“I looked behind him and saw another person standing in a full, dark outfit with a white mask.”

The second person was pressed up against the door. Grant didn’t know what to do except turn the tables on the suspected prankster: He smacked hard on the other side of his front door to startle the person.

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“When I looked out again, I saw the monkey at the window, and he startled me again.”

Grant then retrieved a small machete he keeps in his home and brandished it in the window.

My wife yelled, “Call 911!”

Deputies say they’ve received three to four similar calls over the past month. They urge residents awakened in the middle of the night by banging on their doors and windows to call 911 immediately.

“We take things serious, every time, because until we get there and investigate, we don’t know what the nature of the call is. It could be as simple as a prank to a burglary,” Los Angeles County Sheriff’s Department Lt. John Lecrivain said.

Grant and investigators believe this was a prank, but deputies are concerned that someone can get hurt.

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“They could encounter someone who is armed or who is willing to come out and confront them,” Lecrivain said.