At just before 10:30 a.m., units responded to the intersection of White Marsh Boulevard at Perry Hall Boulevard.
At the scene, witnesses say a military vehicle carrying explosives crashed into a tree.
The driver is currently being evaluated by medical personnel and a perimeter is being established. Route 43 has been shut down between Perry Hall Boulevard and Dunfield Road.
Hazmat crews have been called to the scene.
Motorists should avoid area.