The Lake Grove Shake Shack opened its doors to the public Tuesday, but a few lucky customers got a taste of the famous burgers and shakes a day early during a soft opening on March 6.

This private invite-only event welcomed hundreds of people from Suffolk County to be the first guests of the new Shake Shack in Smith Haven Plaza at the former location of John Harvard’s Brewery & Ale House.

“We’re looking forward to partnering with SBU and having a presence on campus at select sporting events,” Abigail Knoff, the public relations director for Long Island Shake Shacks, said.

Shake Shack is a fast food restaurant that was founded in New York City in 2004. As the chain continues to gain popularity, stores continue to open up past the city boroughs and out east onto Long Island. There are already two locations on the Island, one in Westbury and the other in New Hyde Park. The fourth shack is set to open in Melville in a couple of weeks.

The Family & Friends event held on Monday was a preview for those invited to experience the new store and to give the staff a trial run. Although this was a private event, many members of the community were invited to join, and bring a guest, as long as they had an invitation e-ticket. Invitations were extended to the Stony Brook Athletics Department, the Spirit of Stony Brook Marching Band, and friends and family of Shake Shack staff.

The general manager, Jeremy Graf, pleasantly greeted invited guests at the front door, handing out menu cards for customers to try out their free Shake Shack meals.

“The Lake Grove area is a fantastic area where there’s a lot of diversity, whether it be the college campus or the different communities we have in the area that we thought would be a very enriching part for us and them,” Graf said.

Around 5 p.m. was the peak time for the pre-opening. All the tables were filled and the line nearly extended out the door. Between 50 and 60 people showed up at Shake Shack, ready to be served.

Some of the chain’s most sought after items include its signature crinkle cut french fries, Shackburger, cheese-stuffed Shroom Burger, frozen custards and, of course, shakes.

Stony Brook students were excited to see the East Coast cult food chain so close to campus. It is roughly a ten-minute drive from campus.

“I’m hoping that it’s going to be very good,” Sylvia Nentwick, a senior music major, said while waiting for her food. “I already had a really good interaction with the person who rang up my order. Like she was very into it and very excited to take my order. She answered all my questions and it was really nice.”

Nentwick was invited to the event by Stony Brook Athletics, as she is part of the marching band.

“It was awesome,” Marge Coughlin, a Port Jefferson resident, said. “I had a great experience today. I’m gluten-free and I have celiac disease. [The staff] knew what it was and they accommodated me. They had gluten-free buns for my burger. I can’t get that anywhere.”

Coughlin and her husband were shocked by how attentive the staff was and the level of cleanliness at the location.

“They really made sure there was no cross contamination,” Coughlin said. “They changed their gloves even while serving. I thought this was over the top awesome.”

Dr. Debora Riccardi, the director of community outreach at the Cohen Children’s Medical Center, attended on behalf of the center, which has partnered with Long Island Shake Shacks.

Shake Shack customers can contribute to the children’s hospital by purchasing a specific concrete shake — a mixture of frozen custard and toppings. Shake Shack will donate 5 percent of the proceeds to Cohen Children’s Medical Center.

“The manager at the Shake Shack in New Hyde Park wanted the proceeds to go to the Cohen Children’s Medical Center,” she said. “The entire region picked it up so all of the proceeds from the four stores on Long Island will come to the medical center.

A new Chipotle location is also set to open right next door to the shack, but Graf said he is not too concerned with the competition.

“We all help each other out,” he said. “The fact of restaurants being near each other most [of] the time isn’t taking away. When one’s busier, one can have the overflow and things like that. We really don’t take away from one another.”

Senior psychology major Andrea Bernstein said she plans to frequent both locations, even if her bank account suffers.

“I would probably go to Shake Shack and Chipotle just as often,” she said. “I guess I’ll just be more poor and so will other students,” she added with a laugh.

After the positive response from customers during the soft opening, the Shake Shack staff are confident that the Lake Grove location will be a success.

“I think this new Shake Shack is going to be great,” Nentwick said. “You always need a burger joint close to a college campus.”