Attackers:

To set upon with violent force.

Bandits:

A robber, especially one who robs at gunpoint.

Bombers:

One who makes and sets off bombs.

Captors:

One that takes another as a captive.

Commandos:

A small fighting force specially trained for making quick destructive raids against enemy-held areas.

Criminals:

Of, involving, or having the nature of crime: criminal abuse.

Shameful; disgraceful.

Extremists:

One who advocates or resorts to measures beyond the norm, especially in politics.

Fighters:

One who fights, such as a soldier or boxer.

A pugnacious, unyielding, or determined person.

Group:

An assemblage of persons gathered or located together.

A number of individuals considered together because of similarities.

Guerrillas:

Members of an irregular, usually indigenous military or paramilitary unit operating in small bands in occupied territory to harass and undermine the enemy, as by surprise raids.

Gunmen:

A man armed with a gun, especially an armed criminal or a professional killer.

Hostage-takers: {not found at Dictionary.com]

A group that seizes others against their will to be used as ponds in pressuring authorities to meet their demands.

Insurgents:

Rising in revolt against established authority, especially a government.

Kidnappers:

To seize and detain unlawfully and usually for ransom.

Militants:

Fighting or warring.

A fighting, warring, or aggressive person or party.

Perpetrators:

Someone who perpetrates wrongdoing.

Radicals:

Arising from or going to a root or source.

Departing markedly from the usual or customary; extreme.

One who advocates fundamental or revolutionary changes in current practices, conditions, or institutions: radicals seeking to overthrow the social order.

Rebels:

To refuse allegiance to and oppose by force an established government or ruling authority.

Rioters: [New One]

A wild or turbulent disturbance created by a large number of people.

Separatists:

One who secedes or advocates separation.

Terrorists:

One that engages in acts or an act of terrorism.

The unlawful use or threatened use of force or violence by a person or an organized group against people or property with the intention of intimidating or coercing societies or governments, often for ideological or political reasons.

 

An 'interesting' review of the media's daily description of devout Muslims who attack others: