SEAL BEACH — Authorities investigated a suspicious device that was apparently left sitting on a desk in a building at the Naval Weapons Station in Seal Beach.

Naval Weapons Stations spokesman Greg Smith said someone around 3:30 p.m. left a hand grenade sitting on top of a desk in the station's visitors' building.

The building was evacuated as a precaution and authorities were called to inspect the device. Smith, however, said the device was deemed a harmless practice grenade used in training exercises.

"We're taking every precaution, but the intention doesn't appear to be hostile," he said.

Smith said it's not uncommon for people to find a practice grenade and bring it to the Naval Weapons Station to dispose of the device.

"Sometimes people will find them in their garage and bring these things in but we tell them to leave it where it is and call their local police department," he said.

Authorities were on the scene investigating and had closed a portion of Seal Beach Boulevard as a precaution, he said.