But it's still not clear what caused Friday's fire at the William J. Hughes Technical Center at Atlantic City International Airport.
Fire officials say the blaze began on the roof of a center building and then spread inside it. But no injuries were reported.
The fire made some traffic flow systems unavailable, but didn't affect systems used to directly control air traffic. Traffic flow was moved to a backup system.
Center personnel were being allowed to return to the site Saturday to collect personal items they were forced to leave behind during the evacuations.