After the Joker threatened to blow up a hospital, and doctors and cops in Gotham General (the hospital in which Harvey Dent was kept) started to evacuate patients, a cop said to another cop named Davis, "I'm gonna find a bus for him," referring to Dent, and went out. Only after all the patients except Dent were evacuated, that cop said to Davis in the police radio, "They got space, Bring him out" - but wasn't responded. He hurried back to the hospital looking for Davis, but was shot by the Joker, who has disguised himself as a nurse.
My question is, why was it important to find for Dent an empty bus (Not necessarily completely empty, but mostly)? I tried to figure it out, and I have two possible answers, but they seem pretty weak to me. The first one is that it was for Dent's own safety - he was already injured, and the cops didn't want him to be on a crowded bus where he can be harmed or infected by others. The second one is that the cops didn't want Dent to harm others, because they have already noticed his vengeful desires.
Whatever the reason is, I think it's not established enough, because of another thing that wasn't clear (at least to me): Dent's current status in the eye of the police - was he still considered the White Knight, or was he already considered a potential murderer. Later in the film Gordon was worried about not finding him, but it doesn't strike to me from which reason.