The body of a woman was found Tuesday night floating in a public pool in Massachusetts, and authorities are determining how long the body had gone unnoticed -- possibly since Sunday.

Authorities are investigating how lifeguards and poolgoers at the Fall River facility would have failed to notice the body of Marie Joseph. She reportedly was found floating in the pool by some young people who jumped the fence for a swim while the pool was closed.

The Bristol County district attorney could not confirm that the woman was in the pool during the two days but called the situation “unbelievable,” MyFoxBoston.com reported.

A spokesman from the district attorney’s office told the Boston Globe that the theory that the woman had been dead in the pool for days is “certainly something that’s being looked into.”

Joseph, 36, reportedly was watching her 9-year-old neighbor and had some kind of accident on a water slide. MyFoxBoston.com interviewed the boy’s family, who said he had informed the lifeguards about the accident, but no action was taken.

The entire staff at the Vietnam Veteran’s Swimming Pool has since been placed on administrative leave. The pool is operated by the state Department of Conservation and Recreation. The agency on Wednesday closed all 30 deep-water pools until further notice.

"We will continue to cooperate fully with local and state law enforcement during their ongoing investigation,” the agency said in a statement.