Authorities reveal the surprising way the Ft. Lauderdale shooter got a gun in an airport

Authorities now say the gunman who opened fire at a busy Florida airport Friday killing five people and injuring eight others legally checked his firearm on a flight from Alaska, then retrieved it from his bag when it came through baggage claim.

Law enforcement sources told CNN the gunman, identified as 26-year-old Estaban Santiago, arrived at Fort Lauderdale-Hollywood International Airport on a Delta flight from Anchorage via Minneapolis. The gunman reportedly went through required procedures to bring the gun on the plane. The same sources say after the aircraft landed, the gunman retrieved the weapon at baggage claim, quietly entered the restroom and later emerged shooting.

The gunman was eventually taken into police custody without incident, but not before killing multiple people.

Broward County Sheriff Scott Israel said it's not yet clear whether the incident was terrorism.

Some have already raised questions about the suspect's mental health condition, citing reports he received psychological treatment last year.