“West Midlands Police is currently dealing with an ongoing incident on-site,” a spokesperson for the airport added. All operations were currently suspended.
“Airport operations are currently impacted, and passengers should not come to the airport at this time, the spokesperson said.
Lines of passengers with luggage were seen leaving on foot in posts on social media, with some also at the nearby National Exhibition Centre.
The airport is the seventh busiest UK airport by passenger numbers.
It is used as an operating base for easyJet, Ryanair TUI Airways and Jet2.com.
Its busiest routes are to and from Dublin, Dubai, Amsterdam, Palma de Mallorca and Tenerife-South.Pictures from the airport earlier showed holidaymakers having to line up outside the terminal building.
Some passengers also reported seeing army bomb disposal teams rushing to a car park with police sniffer dogs.All vehicles turning up to the airport were turned away.
A spokesman for West Midlands Police said: "Birmingham Airport is currently being evacuated following a report of a suspicious vehicle.
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"This is a precautionary measure to ensure the safety of passengers and staff."
But in a subsequent update, the force added: "This afternoon, we responded to a report of a suspicious vehicle at Birmingham Airport.
"The safety of all was our primary concern and as a precautionary measure the airport was partially evacuated so the vehicle could be searched and assessed.
A spokesman for Birmingham Airport added: "The airport has resumed normal business with minimal disruption.
"We would like to thank the public for their patience and support while we dealt with this incident."
“Following a Police investigation, some passengers were evacuated and we had to suspend departing flights for a couple of hours.
"That investigation has now concluded, and operations will slowly be returning to normal.
"All passengers are advised to check latest flight information from their airline.
"Whilst we apologise for any inconvenience and disruption, the safety and security of everyone at the airport was our number one priority as we worked through this incident with Police partners."
It comes after passengers earlier described "chaos" outside the airport.
Other travellers told of how they are "stuck" on an plane as police dealt with the incident.
One passenger said: "Very thankful to have managed to get off our flight from Dubai that arrived at 12.30."Chaos outside and had to walk to car park 5 to be picked up by our taxi."
Another added: "My mum and dad are stuck on a plane at Birmingham airport. They have no idea what’s going on they just got back from Spain."
One airport worker said: "It's pretty chaotic. One moment everything is going as normal and people are boarding planes or waiting to go through security.
"Within minutes security are ordering everyone out the building and stopping all the planes on the runways.
