We can read that Umar bin Khattab wanted to attack on other companion during prayer, then Umar bin khattab draged him without investigation and with out true knowledge. We can imagine those extremist who follow Umar bin Khattab they are still following this policy.
We read lots of stories that Umar bin Khattab used to become emotional for such and such reason and wanted to kill unarmed people. Can our Sunni brothers tell us any name that Umar bin Khattab killed or injured any person fighting with him in wars? On the other hand Bukhari testifies that Umar bin Khattab run away in the battle.