The boy was with his father and his two brothers when he fell off the boat.
A 9-year-old boy has been missing since Saturday after he was last seen falling off of a pontoon boat in a lake and being struck by the vessel's propeller.
The incident occurred at approximately 2:39 p.m. on Saturday when authorities from the Polk County Sheriff's Office in Florida were called to Lake Annie -- about 60 miles east of Tampa and 50 miles south of Orlando -- regarding a 9-year-old boy from Port St. Lucie who fell off the front of a pontoon boat that he was sailing on with his father and two brothers, according to the Polk County Sheriff's Office.
"The boy and his two brothers were on his father's pontoon Saturday," authorities said in a statement released on Monday. "The victim fell over the front and was struck by the boat's propeller. The father immediately jumped into the water to look for his son, while one of the other boys called 911 for help."
The young boy was not wearing a personal flotation device when he fell into the water, but was not required to wear one by law.
The Polk County Sheriff's Office have deployed their Marine Unit, the Underwater Search and Recovery Team (USART), the Aviation Unit and Drone Units in the search effort to find the 9-year-old boy. Polk County Fire Rescue, Florida Fish and Wildlife Conservation Commission, and the Seminole County Sheriff's Office have also been involved in the search and recovery efforts, according to authorities.
"It's a tragedy, and an unimaginable nightmare for the family of the boy," said Sheriff Grady Judd in a statement. "We are using extensive resources to find him. We're working in a large lake with depths up to about 16-feet, with poor visibility, but we've been out there 24-hours a day, and will continue to be there until we find him."
The boy's shirt was found wrapped around the boat's propeller following the accident but the boy has still not been found.
"We have searched nonstop since Saturday afternoon and we still have not recovered this beautiful little boy. But we won't give up," Sheriff Judd said.
The investigation and search are ongoing.