Florida officials confirmed that a swimmer was killed by a 12-and-a-half-foot alligator at a central Florida state park on Monday.

Officials say that James Okkerse, 62, went missing in Blue Spring State Park in Orange City just before 9 a.m. Monday morning, while he was swimming and diving in the spring with two friends. His body was found later that afternoon, NBC affiliate WESH reported.

Russell Anen said that he and his wife Carol were swimming and snorkeling with the victim. Russell Anen first spotted the alligator and went to warn the others.

"All of a sudden he just disappeared. Completely gone out of the water, gone. I swam around, looked for him, didn't see him," Carol Anen said.

The Volusia County Medical Examiner's Office ruled that Okkerse suffered from injuries consistent with an alligator attack, the Florida Fish and Wildlife Conservation Commission told NBC News Wednesday. Meanwhile, the alligator involved in the attack was caught and euthanized.

"Our thoughts and prayers continue to be with Mr. Okkerse's family and friends during this difficult time," said Lenny Salberg, an officer with the Florida Fish and Wildlife Conservation Commission, in a statement.

Before the attack occurred, witnesses say they spotted a large alligator in the area where Okkerse disappeared. According to The Daytona Beach News-Journal, the water beast was also spotted twice on Sunday, forcing officials to temporary close the park.

"This is a gator that's been seen in the area. Yesterday they told me they closed the park down twice," Salberg said.

Russell Anen also told the Orlando Sentinel that park officials didn't do enough to warn visitors of the danger of swimming in the spring, especially since the large alligator had been spotted in the area just a day before Okkerse's death.

"There should be more information put out there for keeping the park in control rather than things getting out of hand," Anen said. "We're not foolish people. We should have been cautioned, and we probably would have asked for the size of the alligator."