Heroes may fire ranged weapons when engaged in melee with a few caveats:

• The attacker may only use a power or a one-handed ranged weapon (such as a firearm no larger than a pistol) when in melee. He may not fire rifles or other “long arms.” The TN is the defender’s Parry instead of Short Range as he struggles, wrestles back and forth, etc.
• If attacking a non-adjacent target with a ranged attack while in melee, the attacker instantly becomes Vulnerable.