Incendiary packages detonated in two different government buildings of the state of Maryland Thursday, not far from the nation's capital, dpa reported.
The devices emitted smoke and flames, and burned the hands of two mailroom workers, said Gregory Shipley, spokesman for the Maryland state police, in broadcast remarks.
Shipley said the packages were about the size of a book.
When the employees opened the packages "there was an initial flash of fire and smoke and a smell that emanated from the reaction," Shipley told reporters.
Shipley made his remarks standing outside the Jeffrey Building in the state capital of Annapolis, one of the two buildings targetted and located about 50 km outside of Washington DC on the Chesapeake Bay.
He said the mailroom had been quarantined and the building was evacuated for several hours after the 12:30 pm incident, but workers had returned to work. The second device went off shortly after 12:30 pm in the headquarters of the Maryland Department of Transportation, in Hanover, Maryland, not far from Baltimore-Washington International Airport, about 30 km from Washington.
Both mailroom workers said their fingers had been "singed" but refused treatment, Shipley said.
The investigation was being coordinated between the Maryland state police and the federal joint task force on terrorism.