Two unarmed men early Wednesday worked together to rob a Dunkin’ Donuts store in Shirley of about $400, and the heist was caught on surveillance video, Suffolk County police said.

One of the men entered the store in the 500 block of William Floyd Parkway just north of Northern Boulevard at 2:05 a.m. and demanded money, police said.

The second suspect “served as a lookout outside,” said Suffolk County Police Commissioner Timothy Sini.

No one was injured, police said. And Sini said police don’t believe the robbery is part of an active pattern.

Detectives declined Wednesday to release any video or photos captured of the suspects, police said. Police did not provide detailed descriptions of the suspects, other than to say they were men.

Sini, asked if it was frustrating that a robbery duo had popped up so quickly after police on May 1 arrested a serial knifepoint robber accused of holding up 18 businesses in Suffolk and Nassau since Feb. 13, said:

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“It’s always frustrating when crime occurs. But we live in a county with 1.5 million people, 911 square miles, robberies are down over 20 percent — historic levels. The men and women of the Suffolk County Police Department are doing an excellent job and we’ll continue to stay vigilant.”

Seventh Squad detectives are investigating, police said.