A nuclear site in South Carolina was reopened from more than two hours in lockdown on Monday, after a bomb-sniffing dog over-reacted and halted a delivery truck, the Department of Energy said in a statement.
No explosive residue or device was found on the truck after a search by law enforcement, the Savannah River Site said in a statement on its Facebook page.
The dog had barked at a truck that services vending machines, said an official, who spoke on condition of anonymity.
The facility, which was put in lockdown for a "potential security event" following the alarm, purifies highly enriched uranium and is part of the DoE's nuclear arm.
The Savannah River Site placed its H Area on a "phase II" security alert and personnel were told to remain in their offices or labs until further notice, according to an internal memo seen by Reuters, sent around 3:30 p.m. local time (1930 GMT).