A crew in Ohio caused a building explosion by cutting a gas line thought to be off, as per NTSB.

In Youngstown, Ohio, a deadly explosion at Realty Tower was caused by a crew unknowingly cutting a pressurized gas line they thought was turned off during a basement construction project. The National Transportation Safety Board reported that workers cut the line as part of efforts to clear out infrastructure. The explosion, which killed one bank employee and injured several others, occurred six minutes after the third cut. Investigators are working to determine why the gas line was pressurized. The incident left the ground floor in ruins, sending debris across the street. The tower housed a Chase Bank branch and apartments.