Now, the concern is over the future of the synagogue.
Investigators believe the fire started either on the roof or the top floor, but the cause is still under investigation. The top two floors were completely destroyed, so it may be salvageable because the first and second floors still have electricity.
The fire started around 8:30 p.m. and quickly drew a very large crowd of people who were watching and worrying about the 110-year-old synagogue.
The inferno left little more than a ruin, walls scarred by flames and stained-glass windows melted by the heat. At one point, the fire eating through the synagogue roof grew so intense that firefighters dragged hoses into the building next door so they could battle the flames from higher ground.
Police closed off parts of Lexington and Park avenues during the firefight.
"It's terrible to see it happen," witness Arron Bergman said. "A lot of great events happen there."
"It's just crazy," Danielle Reisman added. "This has been such a part of my life since I was a baby. And now it's just up in flames."
The synagogue was undergoing renovations and was due to reopen in September. Now, that seems to be a dream fueled by determination.
"Thank God nobody was hurt," Rabbi Haskel Lookstein said. "There were no human tragedies here, just the tragedy of the loss of the synagogue."
Because the synagogue was under renovation, all of the religious articles had already been removed.
"My children grew up here, lots of memories," said Mayer Davis, part of the Kehilath Jeshurun congregation.
An overnight fire didn't interrupt Tuesday morning prayers for the Kehilath Jeshurun congregation, but emotions did.
"This morning, when I led the service, I broke down," Rabbi Haskel Lookstein said.
Perhaps because the synagogue's rich history, is also Rabbi Lookstein's family history.
"I've been the rabbi here and my great grandfather came here in 1906," Rabbi Lookstein said.
Still smoldering, firefighters were called back to scene early Tuesday to put out hotspots. The synagogue has been under renovation since early May. Contractors showed up for work as scheduled.
"A building is destroyed, but that's not a community. The community is very, very strong," Rabbi Lookstein said.
Some apartments are damaged, and evacuations building department are doing another assessment. No one has been inside.