LONDON (AP) — British police say two drones found near London's Gatwick Airport were not involved in the disruption that shut down the busy airport just days before Christmas.

Sussex Police Chief Giles York told BBC Saturday police have searched 26 potential launch sites near the airport but do not believe they have found the drone that flew near the runway on Dec. 19 and Dec. 20.

York said he is "absolutely certain that there was a drone flying throughout the period that the airport was closed."

The airport's closure led to more than 100,000 people being stranded or delayed. No one has been found responsible, and York says he is "sorry" about the arrest of two people suspected of involvement who were subsequently cleared.