Crafts in the South of the World

I saw a formation like a cross going from the sky to the sea, descending it seemed. There were 4 perfect balls, and the color of all were silver/grey.
So, then, the one in the lowest position going into the middle of the formation, and then was like a triangle formation.
I was that noght with some friends, having dinner at the Necochea´s beach, in the south atlantic coast of the Buenos Aires province, Argentina.
The night was very clear, and the sky was full of stars. There was not so much wind, and we didn´t drink alcohol, this i want to tell it, because it is important.
10 secs later, the crafts dissapeared, without any signal, in the sky, descending to the sea.
Date is unknown.  PD