You don't know if they have knives, guns, or more friends. You don't know if they would be willing to take your life right then and there. People will take another's life for the most stupid reasons these days. Do not engage in physical conflict. If you feel threatened, call the authorities immediately, and/or run away, there's no shame in that. Be extra sharp, always aware, and be prepared to fight, carry some sort of self-defense weapon with you at all times, but only fight if you absolutely have to.