SKS is the predecessor of the AK
In my opinion a better quality firearm than the AK
SKS that has been in storage and or not cleaned in a while the firing pin may stick in the extended position, so before you load it at the Range just pull the bolt, give it a couple o shakes a touch of oil and all is well.
If you decide to forgo the above and the firing pin is stuck yeah when you let the bolt go it will fire and continue until the mag is empty (as will any semi with the same condition)
The shooter had some AK variant not an SKS ... SKS has a milled receiver the picture of the purps weapon was a stamped receiver
Thank you for the corrections to my info, as you can tell I’m not a gun expert. I’m just posting what I see in the news and online.