Authorities are keeping a close eye on the weather during operations to secure 6 million pounds of explosives at a former ammunition plant.

The National Weather Service says thunderstorms are likely Tuesday in the town of Doyline, located next to the site where the propellant used in artillery shells was haphazardly stored.

State police spokeswoman Lt. Julie Lewis says crews will suspend efforts to relocate the M6 propellant into bunkers if lightning is spotted within five miles of the site.

As of Monday, crews had segregated or safely stored 1.2 million pounds.

In addition to triggering the evacuation of about 400 people, the discovery of the explosives has spawned a criminal investigation of the company that owns the materials, Explo Systems.

Explo has not publicly commented on the investigation.