According to reports, a bullet was retrieved by the FBI from a US Airways plane that left Philadelphia heading to Charlotte Monday night.

The pilot of that plane discovered a bullet hole in the Boeing 737 while performing a routine visual inspection before take off.  The hole was located above rwo 23's window on the left side of the plane.

After further investigation by FBI officials, it was believed the hole was in fact made by a bullet via a small handgun. Authorities however do not know where the bullet came from.

The bullet hole was not considered serious damage and posed no threat to the plane flying safely. Federal Aviation Administration officials said Tuesday that the plane would be put back in service once the hole is filled. 

While the hole was visible outside the plane, it did not go through to the cabin's interior.