2 situations.
1. On the demo the coach in our team was shooting me during a small horde." it's a misfire or he's got bad aim" I thought so I carried on. When waiting for rochelle to spawn from the closet he kept shooting me so I realised he was an ass so I shot him as well. Hearing a hunter I ran out then back in to lure the hunter and the griefer ran out thinking I was gonna run. He gt pounced and I let rochelle out. Later when I went outside he and I were shooting each other, and he incapped me. A teammate revived me(as he shot the teammate incapping me) and then we incapped the griefer.
Later on before the rolling crescendo, we saw him spawn in a nearby closet. Without saying a word, we all passed him and prepared for the crescendo with only 3 people. Thankfully we managed to finish it with ease and all was well.
2.This wasn't an actually attack it was just insults. In dead center, we had to turn off the security alarm since we broke the glass. 1 of us were dead and we were all at red health, taking pills, I ran ahead of my teammates because the horde were gathering and I could draw them away and switch off the alarm at the same time. I switched it off but got jockeyed and died. The good news was that I died beside health supplies and my team could at least get full health. Unfortunately, one of my team members said I was a horrible player for not doing their strategy of killing zombies while standing still in a rolling crescendo so when they finally got near the room, their health had degraded to a 1 hit incap and we failed.