Seven Maryland Penitentiary guards were charged with assault yesterday in Baltimore for allegedly beating three inmates with their fists, feet and riot sticks following the October stabbing death of guard Herman Toulson Jr. in the prison's notorious South Wing.

Baltimore City prosecutor Kurt L. Schmoke said an investigation is continuing and the guards could face additional charges for attempting to cover up the beatings during the trial of inmate Nathanial Appleby. He was convicted of second-degree murder last March for stabbing Toulson, 39, with a homemade "shank," or knife.

"This office wants to be on the record saying you can't enforce the law by breaking the laws," Schmoke said in a telephone interview. "We're still working on the issue of additional charges . . . which could include obstruction of justice." Schmoke said it was the first time in 10 years that criminal charges have been brought against Maryland correctional officers.

The stabbing death of Toulson, the first prison guard killed on duty in Maryland, sparked an upheaval in the administration of the state's prison system, which had been under fire for years because of overcrowding and poor conditions in some institutions.

The Maryland Penitentiary's South Wing, which houses the state's most troublesome and violent prisoners, was characterized by Schmoke during Appleby's trial as "the meanest, toughest area in the meanest, toughest prison" in Maryland.

An investigation of the prison by Maryland Attorney General Stephen H. Sachs after Toulson's death deplored conditions in the penitentiary and particularly the infamous South Wing, calling it the "innermost circle of hell."

Schmoke emphasized yesterday that he was not trying to implicate all correctional officers or demonstrate that beatings are common in state prisons, but his statements did little to diminish criticism from some representatives of corrections officers.

"We are disappointed that the state's attorney chose to take this action. It's going to make morale worse," said Joseph Adler, executive director of the Maryland Classified Employees Assocation, which represents 2,500 prison guards around the state, including six of the seven officers charged yesterday.

"You have to put everything in context and take a look at the prison. Inmate assaults take place almost every day against correctional officers and that should not be lost sight of. Often they have little recourse against them," he said.

Ken Larkin, president of the MCEA local representing 1,350 prison guards in Hagerstown, said officers there were upset. "They don't like to see charges brought against anybody," he said. "It's not good for anybody's morale."

"It's a black day as far as correctional officers throughout the state are concerned," added Samuel L. Stokes, who represents penitentiary guards on MCEA's board of directors. "We're losing the right to defend ourselves."

State police began investigating the alleged beatings in March during Appleby's trial after a corrections officer testified that Appleby and another inmate, Andre Swann, had been beaten in retaliation for the Toulson stabbing.

The third inmate, Kevin Thomas, was beaten for scuffling with a guard after refusing to return to his cell during a security lockup shortly after the stabbing, Schmoke said.

In written reports and during questioning afterward, the guards had maintained that Appleby suffered his injuries, which included a fractured skull, fractured arm and facial cuts requiring more than 108 stitches, during a fall down a flight of stairs, Schmoke said.

"It became clear that several officers had written false reports about how Appleby sustained his injuries," said Schmoke.

The officers, placed on administrative duties out of contact with inmates, were served summonses instead of being arrested and are scheduled to be arraigned Oct. 8.

All have been charged with common law assault, a misdemeanor with no fixed penalty. The officers could receive up to 20 years in prison if convicted, said Assistant State's Attorney Marshall H. Feldman, chief of the grand jury and court arraignment division.

The officers charged: Robert George, 37; Roosevelt Anderson Jr., 29; Irvin Anthony Hawkins, 39; Allan N. Wright, 36; John S. Montgomery, 39; Calvin R. Burkhard, 30; and Larry I. K. Wingfield, 37. All are from the Baltimore area.