An Arizona neuroscientist was arrested Friday at Sky Harbor International Airport after he allegedly pointed an AR-15 rifle at a mother and her teenage daughter.

Peter Steinmetz, 54, was arrested on suspicion of two counts of disorderly conduct for displaying a deadly weapon, according to The Arizona Republic.

Police said Steinmetz was observed buying a cup of coffee in the airport before walking toward Terminal 4’s B gates, where he removed an AR-15 that was slung over his shoulder. Police said the rifle’s muzzle pointed toward a woman and her daughter, who reported fearing for their safety.

Police told the Phoenix New Times that it is legal to carry a semi-automatic rifle into the airport terminal and that in Steinmetz’s case the problem was “the way he was carrying it.”

Phoenix police Sgt. Steve Martos told TV station KPHO that Steinmetz had brought a weapon into the airport before. Steinmetz told officers that he was exercising his Second Amendment rights when he picked up his wife from Sky Harbor while armed with an assault rifle in November, just days after a TSA agent was fatally shot by a gunman at Los Angeles International Airport.

Steinmetz is the program director of neuroengineering at the Barrow Neurological Institute at St. Joseph’s Hospital and Medical Center in Phoenix. The medical center confirmed Steinmetz’s employment Tuesday in a statement but did not comment further on the incident.

“We can confirm that Peter Steinmetz is employed as a part-time researcher with St. Joseph’s Hospital and Medical Center and does not treat patients,” read a statement provided to TPM by St. Joseph’s spokeswoman Carmelle Malkovich. “We are aware of the situation and are taking it very seriously. At present this issue is being handled by Human Resources and our policy is not to comment on HR matters.”

This post has been updated.