SAN FRANCISCO >>  Hundreds of passengers are being rescreened at San Francisco International Airport’s Terminal 3 after a security breach forced the terminal to close.

Airport spokesman Mike McCarron tells KGO-TV the terminal was shut down Friday morning after an incident of unauthorized access between 3:30 a.m. and 4 a.m. He declined to provide details, but attributed the incident to a “procedural breakdown.”

The terminal was shut down and checked. Passengers and employees were rescreened starting around 5:30 a.m.

McCarron says some early morning flights could be delayed.

The terminal serves United Airlines.