Harvey's Resort Hotel bombing
On August 26–27, 1980, several men masquerading as photocopier deliverers planted an elaborately booby trapped bomb containing 1,200 pounds (540 kg) of dynamite at Harvey's Resort Hotel ("Harveys" since 1986) in Stateline, Nevada, United States. During an attempt to disarm the bomb, it exploded, causing extensive damage to the hotel but no injuries or deaths.
Source: Wikipedia — Harvey's Resort Hotel bombing (CC BY-SA 4.0)