Authorities have closed a lava viewing area on the Big Island after discovering an unexploded bomb Sunday morning.

The unexploded ordnance, or UXO, was discovered off of the Hawaii County Traffic Hazard Mitigation Route along Old Saddle Road, according to a news release from the U.S. Army.

Officials said it was found in the lava rocks away from the road, a key east-west highway between Hilo and Kona. Lava from the Mauna Loa eruption has been steadily moving toward Saddle Road over the past week, threatening to close the vital route.

The county, in coordination with Army officials, will be detonating the UXO shortly, the release said Sunday morning.

Officials reminded the public using the Traffic Hazard Mitigation Route along Old Saddle Road to stay on the road, and not wander off into U.S. Army Pohakuloa Training Area training areas. The release said the public must also stay off the surrounding lava rocks, and away from the lava flow.