Jed McLaughlin, the city's police chief, said a "piece of very expensive equipment" was stolen from the Sage Mart convenience store. A home was also broken into, though he said it's unclear what was taken.
It's not immediately known if anybody was arrested in connection with the two incidents. Mayor Peggy Breeden derided those responsible as "bad people."
There are approximately 30 officers from various agencies patrolling Ridgecrest to prevent additional crimes, McLaughlin said.
Fire crews responded to a total of four structure fires, Kern County Fire Department Battalion Chief Dionisio Mitchell said. Three of those fires happened Friday evening, and the fourth broke out Saturday morning in the Town & Country Mobile Home Park in Ridgecrest.
Witnesses said the homeowner was able to escape from the home and used a garden hose to battle flames until first responders arrived. The exact cause of that fire was not immediately clear. Neighbors said they were among the thousands without power late Friday, but electricity was restored at some point overnight.
There are no fatalities or major injuries in Ridgecrest in connection with Friday night's earthquake. No first responders were injured.
There were reports of multiple gas leaks, but PG&E said it was largely able to turn off residential gas lines. Aircraft with thermal imaging technology have been deployed to hunt for any remaining gas leaks.
VIDEO: Moment quake struck Ridgecrest
Kern County Fire Chief David Witt said there were no major building collapses but some structures could be weakened from the back-to-back quakes. Some mobile homes were knocked off their foundation.
Anybody who wishes to have their property inspected for damage should contact the Ridgecrest Police Department.
The American Red Cross opened a shelter at Kerr McGee Community Center at 100 W. California Ave. in Ridgecrest. Public information officer Mimi Teller said the shelter will offer air conditioning, hot showers, sleeping cots and hot meals for up to 500 people for as long as is necessary.
State Route 178 in Kern County was closed by a rockslide and had severe cracking, but CalTrans crews cleared the rocks and patched cracks overnight. All roads in the area are open, but CalTrans District 9 PIO Christine Knadler urged drivers to proceed with caution.
Nearby, the tiny town of Trona, with about 2,000 residents, was reported to have at least one collapsed building. Roads were buckled or blocked, and police put out a call for bottled water for residents.
The quake hit at 8:19 p.m. and was centered 11 miles from Ridgecrest in the same areas where the previous quake hit. But it was felt as far north as Sacramento, as far east as Las Vegas and as far south as Mexico.
The county has opened an emergency shelter. Mutual aid is being dispatched from other parts of Kern County and neighboring jurisdictions.
The Associated Press contributed to this report.