Updated

The Department of Energy’s Savannah River Site announced late Monday it had issued an "all clear" following what it had initially described as a “potential security event” at the nuclear processing site.

A delivery truck triggered the initial alert after a bomb-sniffing dog indicated it could contain explosive residue.

However, the site said an investigation found no explosive residue or device on the truck and operations were returning to normal.

The Associated Press contributed to this report