LOS ANGELES (CNN) -- A busy terminal at Los Angeles International Airport was evacuated Thursday morning after a women carrying what appeared to be a weapon in her carry-on bag slipped away from police.

Airport spokesman Scott Read told CNN that a screening agent at a security checkpoint identified a possible gun in the bag of a female passenger, who was accompanied by a child. Before she could be stopped, the woman picked up the bag and ran.

After the security breach, more than 3,500 people were evacuated from the terminal, which is used by Southwest, US Airways and America West. Three planes had to be deboarded and the passengers rescreened. In all, about 35 flights were affected by the incident.

The woman apparently went home during the evacuation, left the gun there and returned to the airport, where she was detained after police officers recognized her from surveillance videotapes, said airport spokeswoman Nancy Castles.