Some agents associated in some way with the gubmint, most likely. Not as a policy, but to further the leftist/statist wing's agenda.
Gubmint agencies certainly have the expertise to do this, psyche operations have been around for decades now.
To any that scoff at the idea of gubmint agents willingly going along with this stuff, just remember Waco and Ruby Ridge. Those JBTs had no problem at all.
I anticipate we will see ANOTHER mass shooting such as the one in Florida in the very near future. “Strike while the iron is hot”! Pressure is being directed at President Trump and Congress to tighten existing gun laws. Having another large scale shooting will be intended to see more support for greater restrictions when attempting to purchase a gun and eventually complete removal of guns. The movement is well underway, I pray for its total failure.