I walked along the railroad tracks near Hamburg mainstation. It was a clear sunny day and I take a look at the blue sky.I saw 5 objects thats fly in a triangle formation. The objects looks silver/chrome metalic too me and not like normal planes or helicopters.They fly straight horizentally in a close formation and than they instandly switched from horizontally to vertically. There was no curve seeable only direct from horizontal to vertical in a 90 degree angle without loosing formation or distance between it.After a few secounds they loose there formation, speed up very fast and disapears vertical in the sky.I had clear sighting on this objects but loose the sight in one secound after they speed up faster than any vehicle, plane or what ever I see.It looks like speed up from 150 km/h to something around 2000 km/h or more instandly.There was no emission seeable and I dont know a plane or jet without any seeable emmision.