You were just casually taking a weapon to fend off the "smile" infection, which made people excessively aggressive and violent, causing them to harm and or even kill other people.

Until Rob, the one who gives out these weapons, spoke up.

"Please.. Just stay here.." He said, his voice cracking in sadness.

You've never seen him so vulnerable and sad like this.. As he was usually pretty stoic and emotionless.