Earthquake Rattles San Diego 4:00 A.M.

The U.S. Geological Survey gave a preliminary magnitude of 4.0 to the initial quake but downgraded it to magnitude 3.9 three hours later. It struck at 4:06 a.m. and was centered 3 miles east of Jamul, 9.4 miles east southeast of El Cajon and about 20 miles east of downtown San Diego.
The initial shock was followed four minutes later by a 2.4-magnitude aftershock, according to the USGS.
Within minutes of the quakes, dozens of callers phoned the NBC 7/39 newsroom. Many realized that an earthquake had struck, but others said they thought it was an explosion, a bomb going off or a freight train crash. Police and fire departments around the county reported getting similar calls, but there were no reports of damage or injuries.
People reported feeling the quakes as far north as Orange and Riverside counties.