extremely manueverable pulsating white light over Pryamid Lk. shoots straight up into the heavens after investigating(?)the lake over 2

This incident occured in summer of 1968,at appx. 2:am over Pyramid Lake,Nev.,and lasted at least 20 mins.My older brother,his wife,two cousins,and myself had parked on the west side of the lake and were facing it(east)when I noticed a bright pulsating whitish/red light slowly decending out over the middle of the lake.It stopped just above the water and remained motionless for about a minute,then darted to the right extremely fast-so fast it left a "light"trail behind it.It then hovered again silently,and we observed a pale white (light-beam?)emitting from under it,illuminating the water below.At this time my bros. wife began to panic and wanted to leave as did the others.I remained and we saw it manuever all over the lake at different angles,with a somewhat jerky motion-again extremely fast.Finally it was still then suddenly shot straight up and out of sight,leaving a (vapor-trail?) behind it.It seemed to actually blend in with the stars,dissapearing in an insant,veering northward as it went out of sight.The lake is very long and this thing could go from one end to the other ,covering 10+ miles in the blink of an eye,doing right angle turns no aircraft I know of to this day can duplicate.It also seemed to change color after moving,going to a reddish blush and back to white slowly.This is the first time I've reported this incident to anyone.The others are reluctant to talk about it.
Date is approximate.  PD