Security officials closed a concourse at Indianapolis International Airport for about an hour early Wednesday because of a suspicious package that turned out to be an inert explosive used to train federal security workers.
Airline passengers were never in danger, and the Transportation Security Administration is reviewing procedures to prevent a similar situation from happening again, TSA spokeswoman Lara Uselding said.
"A TSA training officer had used the components for training purposes overnight and then inadvertently left them at the checkpoint," Uselding said in a statement.
Airport Police Maj. Tom Hanna said the evacuation was ordered because of the discovery of a vest containing what he described as "inert training explosives" in a tray on a conveyor belt at a security checkpoint.
About 500 travelers were told to leave shortly after 5 a.m., said airport spokeswoman Patzetta Trice.
No flights were canceled, but the evacuation delayed some US Airways and United Airlines flights, airport spokeswoman Susan Sullivan said.