The Rhode Island Fire Marshal said the incidents both took place on Saturday in the towns of Westerly and Charlestown.
The first blast was reported at about 12:30 a.m. Saturday at a residential construction site in the coastal town of Westerly.
“I’ve seen many other things happen to port-a-potties but never an explosion,” Jason Mottle, who has been working the construction site, told WPRI-TV. “The port-a-potty was blown up into a million pieces.”
The second incident was reported hours later in a private parking lot in Charlestown. A fisherman reported hearing an explosion at about 11 p.m. Saturday, but the damage was not reported until Sunday morning.
Images released by the state fire marshal showed both portable toilets blown to pieces.
There were no reports of injuries in either explosion
The state bomb squad, which is overseen by Office of the State Fire Marshal, is now investigating, according to officials. The Rhode Island fire marshal is also offering a $5,000 reward for information that leads to the arrest and conviction of whomever is responsible for the blasts.
Anyone with information is urged to contact the state bomb squad at 401-383-7723.
The Associated Press contributed to this report.