A Memorial Day weekend heist at a state parking garage in downtown Sacramento resulted in 18 stolen state cars.

But details as to how and why the vehicles were stolen remain scarce as the California Highway Patrol investigates, since the parking garage -- located near 10th and O streets -- is state property.

Sacramento Police Department spokesman Sgt. Bryce Heinlein said Tuesday that 13 cars have been recovered so far, with "still a few outstanding."

The vehicles were stolen from the state's Department of General Services.

"We have located a lot of the vehicles unoccupied within the city limits," he said. "We're not real clear on the motive for taking these vehicles."

DGS spokeswoman Monica Hassan said its an ongoing investigation, but noted there were "multiple break-ins" at the garage, which resulted in the thefts, over the Memorial Day weekend.

"Since the incident, the Department of General Services has conducted a security assessment and review of the garage, and has made adjustments to security policies and procedures, including looking into installing an electronic entry and exit system," Hassan said in a statement.

Meanwhile, CHP's press office could not be reached for comment Tuesday.