Don't attack back. Do ask them firmly to sit down and explain calmly what they have to say. Just listening without returning the anger seems to calm them. Don't be intimidated, or let them take over a meeting. Do listen to them and try to benefit from their knowledge.
Victims often complain and feel they are being treated unfairly.
Don't try to become their protector. Do ask them for suggestions to improve the situation. They need practice giving positive ideas. Sarcastic types use words as weapons, often destroying harmony in a group and causing resentment. They can be poor team players.