flies

i came accross this unusual phenomenon some 15 minutes ago. there are thousands of flies partying at the petrol station (under its bright lights). i never knew and expected such scene in town area where the surrounding area are the residential area and industrial area with limited greenery.
i hav no idea what this kind of flies are named, but, i think it's some kind of ant flies.. anyway, it's a horrible scene. only if my car petrol tank is not empty, i wouldn't have step out of my car or stay any longer there... scary...