The 18-year-old who died Friday night after jumping into the Charles River from the Weeks footbridge in Cambridge was a Harvard Summer School student from Georgia named Tyler Greene, according to law enforcement officials and the university. Greene apparently leaped from the bridge at about 8:45 p.m., according to State Police, and witnesses saw him flailing his arms before going under. His body was pulled from the river after a 25-minute search.

“We realize how very upsetting this sad news can be even to those who did not know Tyler personally,” read a letter to the Harvard Summer School Community. “We are all here to help. Don’t hesitate to reach out. …. Our thoughts and prayers are with Tyler’s family and friends in this difficult time.”

A gathering in Greene’s honor was held at 11 a.m. in the Eliot House Junior Common Room at the university, with mental health counselors and clergy members present for support. Dozens of students filled the room, many crying silently and holding each other.

An adult encouraged them to spend time together. Some students remained in the room, while others filed out in small groups, their faces blank.

One summer school student, who gave his name as Brian, said he met Greene only once but recalled him as kindhearted and generous. Brian had forgotten his laundry money, he said, and Greene paid for him.

The tragedy has taken a toll on the tightly knit summer school community, the student said as he left the gathering.

“Everyone tries to avoid the topic,” he said.

Overnight, a small memorial was begun at the bridge, now made of flowers, candles, and half a dozen cans of Arizona kiwi strawberry juice. A simple message was spelled out on small yellow note papers: “For Tyler.”

One summer school student, who visited the memorial with a friend, said kiwi strawberry juice was the teen’s favorite drink.

The student, who asked not to be identified, said Greene, who had just graduated high school, was the first person he had met as part of the Harvard summer program.

“I went out into the yard and he was sitting with a group of people. As soon as I approached him, he immediately took me in and made me feel comfortable,” the student said. “He wasn’t judgey or anything.”

The student said the teen was funny and liked basketball.

“His best quality was that he always had a positive attitude, and he always spread that attitude to everyone,” he said.