The last public comment intake step for NFPA’s Active Shooter/Hostile Event Response Program consensus product happened on February 19th. Additional public engagement with this product is possible at the 2020 NFPA Annual Conference; though that has seen been cancelled. It is likely that committees will be meeting online instead. NFPA is pretty good at letting the world know what they are doing so we encourage to you keep pace from the project page linked above.
For the moment, it is worth noting that some of NFPA 3000 is built on the foundation of recommendations made by the American College of Surgeons — The Hartford Consensus — a consortia consensus product to inform the formulation of policies and procedures to enhance survivability from intentional mass casualty and active shooter events.