Residents of the Washington DC area awoke to quite a shock at 5:04 this morning, when an earthquake struck Montgomery County, Maryland. The U.S. Geological Survey said that the rare 3.6 magnitude quake was centered in the Germantown-Gaithersburg area near the junction of Interstate 270 and Route 119.

Hundreds phoned 911 during or immediately after the rumble, unsure of what was going on. Germantown resident Carroll Ripley told the Washington Post that the earthquake caused her considerable panic.

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"The whole house shook,"she said. "I thought maybe there was an explosion or a plane flew over the house or something. I went straight outside to do a perimeter check -- in my underwear."

No traffic delays were reported in the area, nor was any damage or injury. While the quake caused panic for residents unaccustomed to earthquakes, USGS geophysicist Amy Vaughn told the Post that while quakes of this magnitude were rare on the east coast, they were also not unheard of.

"It’s not something that’s completely out of the ordinary," Vaughan said.

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She did admit, however, that the quake was the largest on record since the USGS began tracking earthquakes in 1974, beating out a 2.7 magnitude tremor in 1993.