Early Wednesday morning just after midnight,  in the 2600 block of E. Rick Drive.  Officers and Saint Clair County Sheriff Deputies responded to a call concerning a hold up of a cab driver at gunpoint.  Port Huron Police say an 18 year old city resident was in custody after allegedly threatening the cab driver with a gun.  The handgun was not immediately located however the suspect was found  about 6 blocks away.  Charges in the case are pending.