Officials in California are reporting an increase in drone usage above prisons throughout the state, recently acknowledging that the unmanned quadcopters have been used to deliver contraband into open recreation yards below — including a variety of illegal narcotics.

In a statement, the California Department of Corrections and Rehabilitation (CDCR) said it “has seen a significant rise in unauthorized drones on prison property statewide in the past year.” The agency is currently looking into repeated drone intrusions at a correctional facility near Bakersfield, where investigators concluded: “Inmates have figured out ingenious ways to introduce contraband into Kern Valley State Prison (KVSP).”

Court documents reveal evidence of several drone drops at KVSP last month. Smuggled items intercepted by prison officials include 15 cell phones, chargers, SIM cards, five hacksaw blades, razors, more than 2.4 ounces of marijuana, cigar wraps, heroin, methamphetamine, a few vials of phencyclidine (PCP), Krazy Glue, and a pair of tweezers.

There is no law in California prohibiting drones from flying over state prisons or county jails. The state legislature passed a bill banning the practice in 2015, but Governor Jerry Brown ultimately vetoed the measure. Since then, drone technology has become an increasing problem at detention centers in the state and all over the nation.

Drones transporting contraband crashed inside the perimeters of at least two correctional facilities in California last year.

In September, authorities at KVSP confiscated one which had been modified with a “release mechanism” carrying “what appeared to be a black cloth like bag,” according to investigators. Search warrants indicate that the drone’s lights “were covered with black electrical tape in order to prevent it from being seen at night.” Officials recovered cell phones, chargers, and SIM cards.

The other drone went down inside the Elmwood Correctional Facility, located outside San Jose. Guards had suspected possible aerial security breaches but were vindicated in October after a small pilotless aircraft crashed in the medium-security jail with a package of meth on board. At least one more drone has been spotted hovering over Elmwood since that incident.

“We don’t know how big the problem is, but there is no downside to being proactive given (Elmwood) is a 62-acre campus with about 2,300 people,” Santa Clara County Supervisor Cindy Chavez told the Bay Area News Group.

Chavez has recommended the county restrict drone activity in the airspace above jails, but experts caution that Federal Aviation Administration (FAA) laws might preempt local ordinances. Her office is currently analyzing the risks such flight paths might pose, including whether there has been unlawful surveillance of the jail.

Meanwhile, the Florida Department of Corrections (FDC) recently confirmed two drone drops on state prison grounds but declined to specify the institution(s) involved. One of those drops carried a cell phone and tobacco. According to the Associated Press, “State lawmakers proposed legislation at this year’s session that would have added prisons and county jails to the list of sites where drone usage is prohibited, but those bills did not pass.”

There have also been problems with drones delivering contraband to state prisons in Ohio, Maryland, and Michigan in recent years.

The Detroit News previously reported, “some drones can carry 45 to 50 pounds of material … allowing them to drop tools or weapons to aid an escape,” and:

Drones represent “a very serious threat to any prison in the United States,” said California security consultant Daniel Vasquez.

Vasquez, a former warden at San Quentin State Prison, recommends the state develop a policy to allow prison guards to “disable or shoot those drones down once they breach the active perimeter of the facility or its flight space.”

But a prison guard would need to be an excellent shot, carry a shotgun at all times and be aided by other guards continually scanning the skies, said Kevin Tamez, managing partner at the New Jersey-based security counseling firm MPM Group. The best bet would be jamming drone signals to shut them down mid-flight, he said, but the Federal Communications Commission forbids any entity but the federal government to do so.

Tamez went on to predict that it will take a significant event before officials enact new drone policies crafted to hinder the flow of contraband reaching inmates.

“When someone drops an AK-47 over a fence … and they have a major riot because these guys have guns,” he said, “then someone’s gonna scratch their head and say, ‘Gee wiz, maybe we should do something about this.’”