The evacuation of Birmingham-Shuttlesworth International airport was prompted by a threat received around 4 p.m., the airport said. The terminal was declared secured around 6 p.m. (7 p.m. ET), and operations have since resumed.
The airport website said several flights into the airport were being diverted.
The evacuation comes just days after a 23-year-old gunman opened fire in the Los Angeles International Airport, killing a TSA officer and injuring several other people.