What Kind of Birds are These?

This huge flock of (some kind of raptor) birds rose into the air and circled on the air currents for about fifteen minutes today soon after the rain began to fall over the lake in the valley below my house (around 3 p.m. today). They reminded me of the scenes I've noted when the Turkey Vultures migrate to this area every Fall. It seems way too late for Turkey Vultures, but since my camera was zoomed to the max and I didn't have time to get out my binoculars, well, I'm just left having to guess what they were and where they were going.