LOS ANGELES, Feb 28 (Reuters) - A total of 325 flights were delayed and hundreds of passengers were evacuated from five terminals at Los Angeles International Airport on Thursday because of a malfunctioning metal detector, officials said. Passengers were taken out of the five terminals during the peak morning period and had to wait for two hours before being allowed back in for re-screening procedures. Airport officials said the evacuation was prompted because "one of the metal detectors at the Terminal 4 passenger screening area under the oversight of the federal Transportation Security Administration was not functioning properly." Earlier reports had said the metal detector was not turned on. "This (the evacuations) follows LAX's security procedures when it is learned that people have entered the secured areas without proper security screening," the airport said in a statement. Stringent security measures have been put in place at airports around the nation since the Sept. 11 attacks on New York and Washington. It was not known how many passengers may have boarded planes without proper screening before the problem was detected. The malfunctioning metal detector was located inside one terminal but authorities were forced to evacuate Terminals 4 through 8 because of the way they are interconnected. The delays affected 325 mostly domestic departures and arrivals of flights on American Airlines , Delta (DAL), United (UAL),and Continental (CAL). Airport officials were unable to say how long flights were being delayed but said passengers were being advised to show up as normal, two hours before takeoff for check-in and screening procedures.