A United flight at Denver International Airport underwent a security sweep after a bullet was found on board Thursday, a United spokesperson confirmed.The bullet was discovered prior to the plane's departure from Denver to San D iego, the spokesperson said. They did not provide further information about how the bullet was discovered or where it may have come from.After the security sweep, the plane was cleared and later departed for San Diego, according to the spokesperson.The flight was originally was scheduled to take off around 1:25 p.m., but was delayed until around 3:40 p.m., flight records show.The incident was first reported by Fox 31, which had a member of its news team on board the flight.TSA officials did not respond to Denver7's request for comment by the time of publication.This is a developing story that may be updated. ...read more read less