The FBI Miami-Dade shootout, in 1986, went so badly that it's still used in police education and science.
The confrontation was between two suspects and eight FBI agents. After exchanging about 150 rounds, the two suspects and one FBI agent were dead. Six agents were wounded, and one unharmed.
I want to understand what happened before it in the FBI as an organization. They were not just shot at like rabbits. There was enough ammunition, enough weapons, they continued shooting when badly injured - nobody behaved stupid. So the problem is inside the organisation "somehow". Much of it is psychology - but I think not everything. I expect many sociological, and maybe some organizational things to play a role.
What actually happened is well known, for a close look at the marksmanship involved, see "FBI 1986 Miami Dade Shooting: An Analysis."
Note that I rewrote much of the text, while the relevant facts are still the same. As in "Ok, most agents did not die. But six wounded is still really bad, right?". I had the facts mixed up with a different shooting.