Fighting endless waves of homicidal lunatics after they lured fire rescue and paramedics on a fake(possibly) call set up just to ambush the fire and medical crews. Managed to get through the whole mission using a combination of blatantly illegal police tactics, plus getting both the medals for nonlethal arrests and headshot kills(2x as many needed than the nonlethal medal; I did say blatantly illegal police tactics), and rescued the majority of the rescue teams.
At one point, when helping the fire crews rescue civilians from a building the maniacs firebombed after the emergency teams showed up, me, the fireman following me, and the wounded civilian the fireman was carrying, get trapped in a pit, and the only way out is through a bad guy who breaks the door down with a circular saw.
Then, when trying to assualt the dockyard crane where the leader was, I start taking hits from guys using akimbo machine pistols. I try to retreat back towards the paramedics to heal, using my Riot Shield of Invincibility and Face-Smashing(actual item, apparently) to ward off the gunmen. I don't get very far before one of them unloads in my back. The last thing I see is my killer standing over me, gloating.
Urban Chaos: Riot Response. I was trying to also get the Survival medal, which requires going through the level without dying once.