LANHAM, Md. (CBSDC) — Dulles Airport is again operating normally after a bomb threat shut down parking garages, runways and delayed flights Monday night.

Metropolitan Washington Airports Authority (MWAA) began investigating the threat around 9 p.m.

Metropolitan Washington Airports Authority (MWAA) say all terminals, runways were reopened around 9:30 p.m. as the airport resumed normal service. The flights being held were allowed to land and proceed to the gate area at that time.

MWAA officials say the economy and hourly parking lots were open during the incident.

The daily parking garages, which became the focus of the investigation, were reopened around 11 p.m. after police finished their search without finding a threat.

Airport officials say passengers should check they status of their flights in case of residual delays