Shark Attack - Bullshark Attacks Spearfisherman

Footage of a bullshark in North QLD Australia cruising on the edge of a channel at 20m turning then rushing and attacking a spearfisherman mid dive. Has anyone seen unprovoked aggressive behaviour like this from a bull shark before?
Updated 13/1/17
Thanks for all the comments and questions so far, i will be posting an interveiw soon to answer as many of them as i can. thanks
Couple of quick answers to tone down the heated comments a tad. I was not there too hunt sharks just fish to eat and i was really disapointed that the shark would of died.