3 lights in sky - Straight line

[astrocreep]

Last night,around 23:30 i saw 3 lights in the sky,moving at a slow pace and they appeared to be following eachother in a straight line. They were spaced apart at around 15-20ft. So either 3 objects were following eachother or it was one very large object with 3 lights. Only the lights were visable and they dissapeared suddenly with no clouds near.

It could very well have been 3 planes but i was wondering what you guys thought,especially as we have a few experts on these boards.