San Francisco Airport has been evacuated and police are on scene amid reports of an unattended bag and a family bypassing security by entering through the exit.
Angry passengers report police swarming the area with planes being moved and people being forced away from the building.
San Francisco International Airport has only said there was an “unattended item” in the Terminal 2 food court and has been accused of handling the situation “ridiculously”.
One person asked “are you waiting for someone to lose it and start a stampede?”
San Francisco International Airport said in a statement on Twitter: “#SFOAlert – SFPD responding to Terminal 2 food court area to clear an unattended item. Food court and D gate areas being cleared out of abundance of caution.”
Traveller Lisa Alpert took to Twitter to alert her fellow travellers.
She said: “Everyone around the Terminal 2, D gate food area were evacuated then asked not to move as security assessed the situation. Security lines were also halted. “