Police in Pittsburgh are investigating a spate of explosions at portable toilets in the area.
Two toilets have been attacked in the past week, with the most recent being on Tuesday morning in the city's North Side.
Police said the explosion happened overnight and a construction worker arrived at work to find the toilet destroyed.
When police arrived at the scene later in the morning, they found "evidence of an explosive device" having gone off.
There were no injuries.
Public safety assistant spokesperson Maurice Matthews told KDKA: "We got pretty blessed and pretty lucky that no one was injured."
Last week another blown-up toilet was found in Lawrenceville, where a 4am explosion sent pieces of the toilet onto the pavement in front of a nearby house.
According to the Pittsburgh Post-Gazette, the homeowner said the blast caused "a loud boom" and broke a window at her home.
The portable toilet had been across the street where another home is being built.
Police have not named any suspects and are still investigating to decide whether the attacks are linked.
