A pipe-like device found inside a mailbox that caused a scare when President Barack Obama was visiting this week turned out to be a fishing device used by thieves to steal mail.

According to U.S. postal inspector Tom Doyle, the thieves use string to lower pipes or wood covered with glue into a mailbox, then lift letters caught on the device, "almost like they are fishing at a lake."

Boyle said the thieves sometimes sit at a mailbox for more than an hour, lifting and then sorting through the dozens of letters they steal, hoping to find money orders, debit cards and checks.

"It’s a federal violation," said Boyle.

Inside the mailbox at East 84th and Madison Monday, the suspect's string broke and the wood and pipes fell into the mailbox. When a letter carrier later opened the mailbox, he saw what looked like a small bomb. 

The NYPD bomb squad was called in, and they determined there was no threat.

Boyle said there have been a dozen cases where postal inspectors have caught suspects “fishing” in New York City mailboxes. He added that cases more often take place along quiet streets, not busy Madison Avenue.

Some residents weren’t laughing about the low-rent crime in this high-rent district.  

“In this neighborhood, I would imagine the quality of the mail would be valuable,” said longtime resident Renee Adams. “American Express, banking. The more I think about it, they picked the right spot.”

Boyle said efforts are underway to catch the suspect for stealing mail and for causing a false security scare.  

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