Here is a very good presentation (h/t @coroldo1) by top expert Della Porta about the SARS lab leaks in 2003/2004.
drive.google.com/file/d/1SMdYzv…
A few images of BSL-3 labs handling SARS at the time: 
Yes, these are BSDL-3 handling SARS back then. 
You get the idea. You can indeed run a BSL-3 as a BSL-2 and and a BSL-4 as a BSL-3. Very easy.
Comes rather naturally if the culture of risk, responsibility and transparency is not there. 
There is only one slide on China because Della Porta was not invited for that investigation (he is clearly too good) and the WHO anyway went missing in action.
The WHO-China investigation became a China-only one with no official report published and an attempted cover-up. 
Anyway I put all the facts together so that you can read what really happened with the Beijing SARS leak.
It's the most complete report available, with no nonsense: I detail a catalogue of gross incompetence, with no consequence for the people involved.
researchgate.net/publication/34…
I particularly draw you to the conclusions in Part #4: 
If you think that the situation is now perfect, and that all belongs to the past, then think again:
gillesdemaneuf.medium.com/evaluation-of-…
Also check (more is coming - there is more data now so this will likely be refreshed):
researchgate.net/publication/35…
For more good analysis papers by Della Porta:
@threadreaderapp compile