I've discussed this at length. The training courses emphasize hide, flee and fight.
All quite reasonable. Each has risks.
In some rampages, the shooter has looked for hiders, shot through doors, etc.
Fleeing if you don't run into the fire zone works, even under fire it might be hard to hit you in a pack. Go for it.
Fighting with improvised weapons just depends on the venue. In some close quarters it has been done successfully but some took rounds.
If the killer sets up to do a large venue, like a theatre or lecture hall - getting to the shooter will be very, very hard. Some bluster that everyone should group into the 300 and charge.
Throwing things is not viable given the distances. We tried a simulation and you just can't throw in lecture room distances. Some charges have been shot down as at VT, IIRC.
The fight part always avoids firearm responses as they are not acceptable. Institutions don't want guns for political and libability issues.