NORTH PROVIDENCE, R.I. (WPRI) — Joann Lyon was getting her laps in at the North Providence Pool and Fitness Center last Friday when the building started rumbling.

“I was the only one in the pool,” she recalled. “All of a sudden, I heard a great big noise. It sounded like a bunch of barrels colliding … like, ‘boom boom bang bang!'”

The 68-year-old decided to continue swimming, and it wasn’t until a lifeguard came over to her and told her to leave that she realized something was wrong.

“He said, ‘Joann, you need to get out of the pool. The jacuzzi just exploded,'” she recalled. “I was grateful that he came right over and told me to get out.”

Shocked, Lyon made her way to the changing rooms and eventually out of the building.

Investigators believe a buildup of chlorine gas underground caused the explosion, according to North Providence Mayor Charles Lombardi.

“The hot tub came right out of the floor,” he said.

The explosion left cracks in the walls and the pool itself, which Lombardi said has since been drained as a precaution.

The building has been closed ever since as investigators assess the damage. Lombardi said he’s unsure when it will reopen, but estimated that it could be a few weeks.

In the meantime, Lyon said she’s been getting her laps in at the Lincoln YMCA.

But some of her fellow swimmers aren’t as lucky.

“There are a lot of seniors that swim here,” Lyon said. “They’re really going to miss this pool … they’ve been coming here for a long, long time.”

“I always say that this pool is the fountain of youth,” she continued. “It makes us young.”

Even though she has a place to swim for the time being, Lyon said she can’t wait to eventually return to the pool she used to visit at least four times a week.

“It’s such a beautiful pool,” Lyon said. “It’s such a nice building … We’re all going to miss it.”

Jake Holter and Kayla Fish contributed to this report.