LAKE RONKONKOMA, N.Y. (CBSNewYork) — A knife-wielding man targeting popular chain stores on Long Island got away with yet another robbery on Sunday.

As CBS2’s Scott Rapoport reported, police Sunday night were trying to connect the dots in a possible pattern that has businesses on end.

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Suffolk County police detectives wasted no time – at least six of them could be seen at The Barn in Lake Ronkonkoma after it was robbed shortly before noon, 1010 WINS’ Carol D’Auria reported.

The Barn is a drive-through convenience store located on Hawkins Avenue. The suspect was caught on security cameras, but the video has not been released.

The robbery fits a pattern, making it the 17th time a robber has hit with a knife or machete.

“We got robbed,” store clerk Liz Calabrese told CBS2’s Scott Rapoport.

Calabrese said another woman was on duty at the time of the crime, but she said the whole thing has left her rattled.

“Basically the guy just came in. He wanted money,” she said. “She stepped away, let them take what he wanted, and he left.”

The scene has been repeated over and over again at chain stores such as Carvel, Dunkin’ Donuts, TCBY and Subway. Even another location of The Barn in West Babylon was hit less than three weeks ago.

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Andrew Liu’s Carvel store in Westbury, for one, was robbed on March 27.

“It’s kind of frightening but considering it’s been going on, I kind of suspected something might happen,” Liu said. “I was hoping it wouldn’t.”

Police believe the robberies of 10 stores in Nassau County and six previous ones in Suffolk County are all part of the same disturbing pattern.

“It’s horrible. It’s terrible,” said Mark Grimaldi of Lake Ronkonkoma.

“You have to be vigilant. You can’t stop living life,” another woman told WCBS 880’s Sophia Hall.

In each case, police say, the suspect — flashing a knife or machete – forces employees to clean out the register and then bolting. So far, CBS2 is told, no one has been injured.

But that does not change he thought that many around here can’t get out of their head. …

“The fact that there is someone walking around town carrying a knife that could actually injure someone hurt someone,” said Victoria Smith.

“It is scary,” added Calabrese. “I try not to think about it.”

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Suffolk County police Commissioner Timothy Sini has said the robber keeps eluding capture because he works very quickly and his face is usually covered.