HOUSTON -

Thieves are gaining access to Houston drugstores by cutting holes in the roof. Since April, three Houston pharmacies have been burglarized this way.

An aerial view shows the hole on the top of a southwest Houston Walgreen's at Belfort and MLK. On Thursday, thieves used the hole to get inside the building and steal prescription drugs. It also happened during the early morning hours of May 17 at a Walgreen's on Chimney Rock. A CVS in North Houston was hit also on April 11.

The method of entry has been seen before, and some pharmacists are now taking extra measures to protect their businesses.

Hazel's Compounding Pharmacy in Pearland was targeted last year, just three months before Dr. Tracey Benson bought the pharmacy. Since then, she's added more security camera cameras and anchored her safe to the ground. She also had the building's walls reinforced.

“Now it's just more lasers, more security,” said Dr. Benson.

Zeke Peinado with American Sentinel Fire and Security designed the pharmacy's system and several others.

He told Local 2 some pharmacies have also started adding photo beams in the ceiling to detect motion.

“We want to make sure you can't go three to four steps without setting off an alarm,” said Peinado.

According to RxPatrol, a database created by the Purdue pharmaceutical company to track prescription thefts, Texas leads the nation in pharmacy burglaries. Their latest numbers show there were 110 burglaries and 17 robberies in Texas in 2011 and 2012. Houston accounts for 28 of the burglaries and one of the robberies.

The threat has prompted Benson to install bullet proof glass at the drive through window, allowing for her employees to be protected.

 “You see more break-ins, more daytime robberies. You would never see that in a pharmacy,” said Benson.

The Houston Police Department is investigating the most recent robberies. At this point, it is unknown whether they are related.