These days, aggressive behavior seems out of control. It's not uncommon to see people fighting, in homes, at sporting events, on public transportation, in school, or even at the work place. Intervening in a physical or verbal fight can be dangerous, but sometimes it is the right thing to do. There are several strategies you can try to de-escalate these types of situations.
1- Intervening in a Fight
Stay calm. If two other people are starting to fight, you should try to diffuse the tension by appearing relaxed.[1] Use a soothing tone of voice, nonthreatening body language (for example, keep your hands raised in front of your chest), and slow movements.
2- Assess the situation quickly.
Fights move quickly so you won't have a lot of time. You need to determine how serious the situation is, if you are in danger, whether you need to call for help, and what strategies might work best to stop the fight in this particular situation. Try to determine whether anyone has a weapon or is likely to reach for an object to use as a weapon (for example, a bottle in a bar fight). If so, call the police and do not intervene. Try to move other onlookers, especially children, to safety. Notice whether the fighters have "back up," often in the form of onlookers who are egging on the fighters. Gang fights and similar situations are unpredictable and you should not try to intervene. Look around for any large objects that you can push between the fighters, like trash cans, desks, or anything else that is big but possible for you to quickly move into place.
1- Call the police.
If either fighter has a weapon of any kind, call the police and do not try to intervene. You should also call the police if you are physically unable to restrain a fighter or fear that your safety would be in jeopardy if you intervened. Unless a police officer happens to be in the vicinity, it may be too late by the time they arrive. If it is safe to do so, try to break up the fight yourself while you wait for them to arrive.
4-Get help from another onlooker
If there is anyone else within hearing range, get them to help you break up the fight before attempting to do it yourself. In situations like this, onlookers don't generally stop to help unless you tell them specifically. So instead of yelling "Someone help me!" look someone in the eye and say "Help me stop the fight!"[2] If possible, choose someone who is larger than the fighters and looks strong and athletic. But in a pinch, any able-bodied adult will do! Don't leave the scene of a fight to get help unless you have to, especially if the fighters are juveniles. If you're at school or in another setting where there are no adults present, you can always send a kid to get another adult.
Source :https://www.wikihow.com/Stop-a-Fight