Story highlights Police did not find anything suspicious during their security check at Phoenix airport

47 passengers were removed from United Express Flight 5573

United Express Flight 5573 from San Francisco to San Antonio was diverted to Phoenix Sky Harbor International Airport Thursday afternoon when a crew member discovered an undisclosed security threat, according to Phoenix police.

The nature of the apparent threat was not known, and after an investigation and a security check were completed, nothing suspicious was found, Phoenix police Sgt. Steve Martos told CNN affiliate KPHO

The plane had been diverted Thursday afternoon, and Sky Harbor officials said passengers were removed from the airplane and rescreened. The airport was not evacuated.

The small commuter plane carried 47 passengers.