The body of a 5-year-old boy last seen watching cartoons at his Virginia home on Sunday was found in a septic tank, sheriffs said late Thursday.  

Noah Thomas was found dead in a septic tank in Dublin, Va., at around 1 p.m. Thursday during what Pulaski County sheriffs called a "detailed and aggressive search," WDBJ reported.

"He was found at a location near his home," Sheriff Jim Davis told the station. "The recovery of the body is now part of our investigation, and ongoing."

Noah's mother said she last saw her son on Sunday morning watching cartoons in the living room of their Highland Road home, according to HLN-TV.

Police did not release many details except to say dozens of investigators were working round the clock to determine how the 5-year-old ended up in the tank. Hazardous material specialists were sent to the scene on Highland Road from Roanoke to help handle the recovery.