San Jose police said they arrested a 23-year-old man late Thursday night after they found him with an AR-15 assault rifle and three loaded magazines in the trunk of his car.

Police arrested Israel Valenzuela at 11:53 p.m. at S. Fourth and E. San Salvador streets.

Sgt. Jason Dwyer said a woman who was sitting in her parked car on the second level of a parking structure nearby, reported seeing Valenzuela flash a large black gun to his friends, and then tuck it away in his trunk before heading out of the parking garage.

When police caught up with him later, Dwyer said they found a round in the chamber. And the gun was loaded with a 30-round magazine.

Officers also located in the trunk: two additional 30-round magazines, two empty magazines and three boxes of military-grade ammunition.

Valenzuela was booked into Santa Clara County Jail for possession of assault weapons.

That particular weapon is banned in California.

Contact Lisa Fernandez at 408-920-5002. Follow her @ljfernandez.