Escape london city airport

You and your security team just pull in to the Airport car park for the start of your shift, when suddenly the air siren starts to sound....?.....that hasn't gone off before you think to yourself, ever!
Suddenly to the east you hear loud cries and from a distance you can see a swarm of people covered in blood running towards you....they looks crazed, and at that moment you watch in horror as one of them starts devowering someone as they run to a nearby car.
All three of you grab your guns from the boot of the car and start to run west towards the back entrance of the airport.
"we have to get to my friend who is a pilot, he will get us out of here......he should be in one of the aircraft, lets get to him and get out of here, we will have to go through the airport check in area first then out to the plane".