Jan 26, 2010 11:50 AM by Jackie Bensen, NBC
A scary moment in suburban Washington DC Monday, triggered by an underground explosion.
Utility crews in Wheaton, Maryland, are trying to figure out what caused the blast.
A manhole cover that can weigh as much as 100 pounds went airborne.
It crashed through the windshield of a Mercedes SUV and struck the driver in the face before landing in the back seat.
The driver was seriously injured.