Observed 3 white lights lines up like traffic lights,then went into a triangle formation and could barely make out the shape,jet black in colour,dissappeared into the clouds.

I was just about to walk in from my front yard when I noticed 3 light lined up like traffic lights,I pointed it out to my brother who couldnt work out what it was,maybe 3 helicopters pulling fancy manuevers?We called several more people out inc neighbours who had also seen it,the 3 lights then moved upward serveral hundred feet and went into a triangular fomation,then several minutes later you could barely make out a jet black triangle(with binoculars)it stayed still for a good 15-20 minutes before dissappearing behind the clouds.It was the only UFO sighting I have ever seen and the wierdest thing Ive ever seen,guess me may never know what it was.