Miami 2 die and 5 are injured as a tower section is dropped during a climb.
The section of tower is 20 feet long weighing in at 14,000 lbs. The crane appears to be a 500 HCL Liebherr. The transfer of the tower from the hook to a trolley device on a beam is one option for how this accident could have happened. One scenario for rigging this tower off of the picking device seen on top of the tower could leave endless rigging without a positive attachment. Meaning if the tower is not settled in properly in the trolley device but the rigging becomes slack due to say poor communication, the rigging could dislodge from it's placement.
Of course it's possible to have the entire beam fail to support the tower or the end trolley stops fail, but again, it's an on going case so infomation is sacred at this point. Achims razor would suggest the first scenario I laid out. If you look at the picture of the tower in the house, you can see the vertical member bent to the left suggesting that the tower was hanging by one ear for a moment before the dismount.