LAWRENCE, N.Y. (CBSNewYork) — A Long Island community was in a panic late Thursday after a 29-year-old medical student vanished.

As CBS2’s Jessica Schneider reported, Yosef Gerson – known to family and friends as Yossi – was last seen Monday when he left his family’s home to meet up with a homeless man he had befriended.

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Gerson is a medical student at the Albert Einstein College of Medicine at Montefiore Medical Center in the Bronx. But recently, he has been stressed and not himself, according to his family.

And now he is gone.

“Honestly, we don’t know anything,” said Rabbi Boruch Bender, a family friend. “We just know that he’s disappeared, and unless we’re told otherwise, we have grave concern for his safety.”

Now, dozens in Gerson’s Five Towns community in Nassau County have mobilized – putting up posters and scouting hospitals, hotels, and neighborhoods, and trying desperately to get any clues as to where Yossi Glasser might be.

He was last seen by his mother Monday morning.

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“We’re begging you to please come home; to call; to just come home,” said Wendy Gerson. “We’re all here. We’re waiting for you.”

Yossi Gerson told his mother he was coming to Woodhaven Boulevard in Queens to visit a homeless man he had befriended.

Police have interviewed the homeless man, who said he last saw Gerson Monday evening.

“They did speak with this individual. They do not believe he’s a person of interest. They do not believe he knows where Yossi is either,” Rabbi Bender said. “This person is someone that Yossi appreciated, and at this point, they do not believe that he has any information as to where Yossi is.”

As of Thursday night, the whole community had already been through two nights of searching. They said they would continue until Yossi Gerson was found.

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The family is also offering a $20,000 reward for any information.