A 4-year-old Louisiana boy is presumed dead after he disappeared Thursday in a swamp at a national park in Louisiana.

Jefferson Parish Sheriff Joseph Lopinto said the Marrero boy disappeared at Jean Lafitte National Historical Park and Preserve in Marrero, Louisiana at approximately 5:30 p.m. Thursday.

“We currently have no evidence that the child is on land, and search efforts are now focused on the area waterways,” Lopinto said. “The land in the area the child was last seen has been thoroughly searched by multiple parties.”

WWL-TV identified the boy as Ellis Boudean and reported he has autism.

New Orleans area media reported the mother had turned her back for a few seconds to fix a kite they were planning to fly, heard a splash and turned around to see the child’s 3-year-old sibling pointing at the water.

Lopinto said they believe the child simply jumped into the water and drowned.