Humm. I've been a model flyer on and off for 40 years. It's very common to claim interference caused a crash.... Oh look I have no control therefore it must be interference and can't possibly be my fault... when in reality there could be any number of causes. Low receiver battery, faulty wiring, faulty mechanics, unseen previous crash damage etc
I haven't bothered to investigate what model of drone was involved in the above incident but don't many that size claim to have some sort of fail safe, hover on the spot or return to base function in the event of loss of valid signal? Why didn't that work?
I highly doubt the crash was due to signal interference. If it was the operating company is completely unqualified to be operating drones around people.
The flight software can be programmed to do any number of safer things given a loss of signal: hover, land in place, return to base, maintain course and altitude. I can hardly believe a professional drone filming company would set their drones to "plummet to the ground" on signal loss (and yes this is an option).
I would guess it was caused by some sort of mechanical failure. Like any other machine, parts can fail, solders can crack, propellers can shatter, etc.