A 21-year-old lifeguard was found dead in a North Carolina YMCA on Thursday morning.

According to the Charlotte Observer, Yesenia Jimenez Linares, 21, was found face-down in a pool at the Lincolnton YMCA where she worked

Linares’s’ co-workers reported her missing early Thursday morning, when they arrived to find the pool still locked from the night before. Linares had been scheduled to open the YMCA around 5 a.m., and the pool would typically have been unlocked by the time her co-workers arrived.

Police were called to the scene, and found the young woman unresponsive in the pool. Linares was taken to a nearby hospital where she was pronounced dead.

The circumstances of the apparent drowning are not yet known.

Linares had reportedly worked at the YMCA since 2014, and was a beloved member of the staff.

“Our Y family is heartbroken and fully focused on supporting the family, along with our entire branch staff and members,” YMCA spokesperson Molly Thompson told the Charlotte Observer.