Jail-house assassins fired five bullets Saturday into a cocky icon of Protestant militancy who some fear could do as much damage to Northern Ireland peacemaking in death as he did in life.

An Irish Republican Army splinter gang killed Billy Wright, widely known as "King Rat," inside Northern Ireland's top-security Maze prison.Police closed roads in religiously divided west Belfast and kept watch elsewhere for possible retaliatory strikes against Catholics.

Despite appeals for calm by political leaders, the slaying unleashed violence. Late Saturday, gunmen opened fire on customers departing the Glengannon Hotel in a mostly Catholic area near Dungannon, 40 miles west of Belfast, and wounded four, including a 14-year-old boy.

A spokesman for the South Tyrone Hospital told Reuters that two of the victims, one age 39 and one age 44, were in "critical condition with life-threatening injuries."

The others, the 14-year-old boy and a man age 47, were said to be in serious but stable condition. According to media reports, the victims included doormen at the Glengannon Hotel.

It was the first apparently sectarian gun attack on a public place in Northern Ireland since 1994, when paramilitary groups began observing matching cease-fires.

In another incident, masked Protestants commandeered at least six vehicles at gunpoint and set them on fire.

Many Catholic-frequented pubs and other social venues closed early after dark in fear of possible attack.

Both Wright and his killers opposed the cease-fires that have opened the way for negotiations on the future of British-ruled Northern Ireland.

Moderate Catholic political leader John Hume warned that Wright's assailants "have the success of the entire peace process in their sights."

Wright, 37, was the defiant leader of the Loyalist Volunteer Force, a growing pro-British paramilitary group that he founded last year to oppose the peace strategy of his former comrades in the Ulster Volunteer Force. He became a hero to Protestants opposed to negotiations with Sinn Fein, the party allied with the IRA.

One or more imprisoned members of the Irish National Liberation Army shot Wright in the back from a nearby roof while he was being escorted by unarmed guards to a visiting area at the Maze, 12 miles southwest of Belfast.

Three Liberation Army members handed over two smuggled handguns to a Catholic chaplain and surrendered to police within five minutes of the shooting.

It was the first assassination of a Maze inmate and came as 161 other prisoners were enjoying a special Christmas parole.

Wright, dubbed "King Rat" by the tabloid The Sunday World in 1990, was the most ruthless figure to emerge from Northern Ireland's pro-British paramilitary groups.

He survived a half-dozen IRA assassination attempts and shrugged off a death threat from his Protestant former comrades.

A forbidding figure, Wright admitted in a 1992 interview with The Associated Press that he had planned the killings of more than a dozen Catholics, including two members of Sinn Fein.

He insisted that each victim had secret IRA associations, and called his approach "terrorizing the terrorists."

On Saturday, Protestant politicians, already furious over this month's escape of an IRA prisoner dressed as a woman, demanded the resignations of Northern Ireland Secretary Mo Mowlam and prisons chief Alan Shannon.

Mowlam said Wright's killing was a serious breach of prison security, but added: "Resignation at this stage would be an excessive step."