Paul Ferguson, who was working in a nearby office, saw this morning's helicopter crash.
There was a flash and the helicopter plunged to the ground. It exploded and you can imagine the smoke coming out of it.
It was probably heading from the nearby heliport. It may be that on this misty morning the lights on nearby St George's Tower weren't on and it moved and clipped the edge of the crane and lost control.
More top news
David Cameron will be facing a hostile audience when he meets with leaders from the remaining 27 EU nations this week, writes James Mates.
Baroness Warsi warns reports of hate crimes are rising after a "divisive" EU campaign largely focusing on immigration spurred street abuse.
Labour has descended into crisis as several high-profile members of the shadow cabinet have quit in the past few hours. Here's who they are.