After a string of thefts on June 1, the Detroit Zoo said that it would add surveillance cameras and take other steps to beef up security, according to an article from the Detroit Free Press.

Six vehicles, all minivans, were broken into and were missing in-dash stereos, DVDs or GPS systems, according to Royal Oak Police. A seventh minivan had pry marks, showing that someone had attempted to break in, the article says.

All of the vehicles had been parked in the zoo’s parking structure, just outside the main gate, police said.

On the same day, a zoo visitor reported that her purse was stolen by an unseen thief while she was inside the zoo near the lion exhibit, according to the article.

The zoo has had occasional thefts but never so many in one day, according to spokeswoman Patricia Mills Janeway. She said that the zoo has had an unusual spring with excellent attendance, including 19,000-plus visitors on April 7 for the Bunnyville event.

Janeway said that the zoo has regular security patrols in all of the parking areas, and there are security call boxes with direct connections to zoo security officers, the Free Press reports.