The explosion of a packaged "incendiary device" in a suburban St. Louis parking garage on Thursday shook an office high-rise and surrounding buildings, forcing hundreds of people to evacuate.
The Associated Press reported that a 69-year-old man was injured when he picked the package up shortly after 11 a.m.; his injuries were not considered life-threatening.
Officials would not elaborate about the type of device used or whether the victim was the intended target.
The device was found in a parking garage tat is shared by an office building and a residential complex; no damage was seen from the outside of the buildings.
The Ritz-Carlton St. Louis was among the buildings evacuated in Clayton, Mo., a suburb of St. Louis. A spokesman for the hotel said the building was evacuated as a precaution, but everything was business as usual by the afternoon.
Searches of nearby buildings by local authorities, the FBI and the Bureau of Alcohol, Tobacco, Firearms and Explosives, did not turn up any additional devices.