Schwartz had been accepted to college in the United States but decided to spend a gap year in Israel at a yeshiva, a Jewish educational institution where students study religious texts.
The 18-year-old was volunteering in the West Bank on Thursday, delivering food to Israeli soldiers, when he was killed.
"That was just the kind of kid he was -- making sure the people around him were taken care of," his longtime camp counselor, DJ Niedober, told CNN.
At a crowded intersection in Gush Etzion, an unidentified gunman fired shots from his vehicle and rammed pedestrians at a busy intersection in, killing three people, including Schwartz.
Israel Defense Forces said that the attacker was Palestinian. Police have issued a gag order barring the media from reporting any details of the investigation and anything that could identify the suspect.
"Ezra came to Israel not only to study but also to be a part of the vibrant Israeli experience," Natan Sharansky, the chairman of the executive for the Jewish Agency for Israel, said in a statement. "This makes his death even more tragic."
Schwartz, who was from the Boston suburb of Sharon, loved sports and was a very active, energetic kid, Niedober said.
"The only thing he really cared about was having fun, you know, and having a good time -- and making sure the people around him were having a good time," he said. "We knew he could do great things, and he was just starting to."
William Barry, who calls Schwartz one of his best friends, met him at summer camp when he was 10 years old.
He told CNN in an email that Schwartz was one of the "most loving, caring and fun-loving people" he knew.
"He lit up every room he entered and knew how to make anyone smile no matter how upset they were," Barry said. "Ezra leaves this world as a kind, caring brother, friend and role model to many, but his lasting memories and love will never be forgotten."
Schwartz went to high school in Brookline, Massachusetts, and graduated this year.
"The whole school went into shock," Lori Kipnes, a teacher at his alma mater --
the Maimonides School -- told CNN affiliate WCVB
"We watched him grow," said his rabbi, Meir Sendor. "It's devastating. It's heartbreaking."
The funeral for Schwartz will be held Sunday in Sharon.