Indiana is leading the nation in pharmacy robberies, USA Today reports. The Drug Enforcement Administration says there have been more than 130 such incidents since the beginning of 2015.

CVS/pharmacy has announced it installed time-delay safes in more than 150 stores in the Indianapolis area. These safes require pharmacy employees to enter a code, and then wait before a safe will open. Walgreens installed time-delay safes in Indiana last year.

Officials are not sure why pharmacy robbery rates are climbing higher in Indiana. The article notes the state has cracked down on pill mills, where doctors overprescribed prescription painkillers. It is also harder for people to obtain painkiller prescriptions for nonmedical use because of the state’s prescription drug monitoring database, which identifies patients who fill multiple prescriptions.

These efforts may have inadvertently led to more pharmacy robberies, according to Ted Cotterill, Director of the Indiana Board of Pharmacy. “While we have tightened the grip on prescribing and dispensing, we may have just driven that traffic elsewhere,” he said.

While in past years, most robberies were committed by people who were addicted to the drugs they were stealing, many recent robberies have been committed by people who plan on selling the drugs.

In March, Indiana Governor Mike Pence declared a public health emergency as the state battled an outbreak of HIV linked to intravenous use of the painkiller Opana. Earlier this year, Governor Pence authorized a short-term program in one county to exchange used needles for sterile ones, to reduce the risk of contaminated needles being shared. In May, Pence signed a law that extends the program, allowing Indiana localities with health emergencies to begin their own needle exchanges.