The agents, from the Bureau of Alcohol, Tobacco and Firearms, are searching the premises to ensure there are no further explosives on the property, WFAA-TV, Dallas, reported Monday.

Police said Mary Creecy reported finding one of the grenades while doing yard work.

The Plano Police Department bomb squad arrived on the scene and safely detonated both grenades. There were no injuries.

The origin of the objects is not yet known.