Stephanie Morse

Arizona Republic

Arcadia High School in Phoenix was on lockdown Monday after a nude man carrying a briefcase was seen running in the area, officials said.

Police said the man ran through the school's parking lot and then into an intersection at 48th Street and Indian School Road, according to a statement from the Scottsdale Unified School District.

High school junior Grayson Belfer said he saw the naked man run through the school's parking lot at about 11:50 a.m.

"He dashed in front of my car, and (I) slammed on the brakes," Belfer said. "He then ran through the parking lot in between cars into the intersection and stopped traffic."

Belfer said a police helicopter overhead cautioned students to leave the parking lot and go back inside the school.

The man was wearing only socks and dress shoes, Belfer said.

As a precautionary measure, Arcadia High School was put on modified lockdown around noon and it was lifted about 30 minutes later, the school district said.

The man, whose identity was not released, has been detained, according to Phoenix police Lt. Vince Lewis.

His behavior was likely caused by drugs, Lewis said.

Police have not made public the contents of the briefcase.