*sigh*
Small caliber semi-auto handgun.
Probably from the stands to his right rear (viewers left). We'll have to wait for video from or of that location (and there will be at least some) to confirm what happened to the flurry of follow up rounds that were fired. It's possible those were fired as the shooter was being tackled by bystanders.
Not a professional.
@Render
Yes, thank you, You are awesome. Am sending hugs
@artemis
Keep reading the thread. Almost everything in the 1st post is wrong.