A knock at the door turns into a nightmare for an elderly valley couple.  Both were tied up and robbed by two strangers who convinced them to open up.

This most recent incident, near Desert Inn and Theme, marks the third attack on the elderly at home here in the valley over the past month.

That includes a 65-year-old woman who was reportedly punched 40 times by a man who claimed to have lost his dog.

In this latest case, the two suspects told the couple that their basketball went over the fence and into their yard.

Once the door was cracked open, police say the duo barged their way in with a gun and ransacked the home.

The elderly male victim was reportedly punched in the face several times before the men took off.

Neighbors who live in the area are now weary to open their doors for anybody.

"My mother would be the one to do that. I'm just going to make sure she knows that she needs to look through the peephole always," said neighbor Jeanne Voltura.

Police are lending their advice following this alarming trend - never open your door for a stranger, no matter how convincing their story may be.

Metro is hoping for the public's help in tracking down these two suspects. 

They're both described as African American adult males, around six feet tall, between 190 and 220 pounds.