Authorities are investigating a knifepoint robbery at a Carvel ice cream shop in Lake Ronkonkoma over the weekend, Suffolk police said Sunday.

No one was injured in the Saturday night holdup in which an undetermined amount of cash was taken, police said.

Despite the suspect’s use of a knife, police said a preliminary investigation has not produced evidence linking the robbery to a pattern of machete and knifepoint robberies committed by a masked man in Nassau and Suffolk over the past six weeks.

But detectives are still investigating any possible link to that pattern or any other active cases, police said.

Meanwhile, Carvel corporate officials have sent an advisory to its Long Island stores alerting the business owners to the crime wave.

“The safety of our franchisees, their employees, and customers is paramount,” said Carvel spokeswoman Loryn Franco in an email Sunday. “The franchisees involved are cooperating with authorities and following all safety and security procedures. We will continue to closely monitor this situation and urge all Carvel franchisees to be conscientious and enforce proper protocol.”

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According to Suffolk’s Fourth Squad detectives, the robbery occurred about 9:20 p.m. Saturday at the Carvel at 290 Ronkonkoma Ave.

Details about the robbery — including whether the suspect covered their face, the kind of knife used, or how much cash was taken — were not available Sunday, police said.

A description of the suspect was not provided.

The unsolved robberry pattern, which began six weeks ago, includes four holdups and an attempted robbery in different locations in Nassau and the holdup of a Copiague Subway shop in Suffolk.

That suspect has alternately used a large kitchen knife or a machete during the heists.

Authorities investigating the robbery pattern have said they believe one male suspect may be responsible for the crimes because of his clothing, build and the type of weapons used.