My sincere sympathies.
Details are sketchy, and as mentioned in the report, the whole tragedy is being investigated. I do not wish you to think I am speculating on causes etc as this is neither the time nor the place.
However, an heroic attempt was made by one man, to grab hold of the balloon and weigh it down. Unfortunately the freak gust was stronger, and caused him to be swept away as well. He was able to let go, but was seriously injured as he fell to the ground.