Nine prisoners escaped from the Prince George's County Detention Center early yesterday after hacksawing through a third-floor window only several yards from where a guard sat in a glass booth.

Detention Center Director Arnett Gaston absolved the guard of blame, suggesting that in addition to having difficulty seeing in the darkened cell block, he may have been distracted by other inmates.

The escapees, who apparently jumped or lowered themselves to the ground on ropes, were still at large last night. All were in the Upper Marlboro jail awaiting trial, seven on armed robbery charges, one on a drug charge and one on a charge of violating probation. The break was discovered about 4:30 a.m. by trusties who arrived at the section and found they had more breakfast trays than prisoners.

Before reaching freedom, the inmates also had to avoid detection by another guard, Michael Sofidiya, who was walking around the outside of the jail. Gaston offered as an explanation that "when he Sofidiya was on one side of the jail, they were jumping down on the other side."

Several guards who did not want to be identified said that during the weeks before the escape they had found in the section "a rope strong enough for an elephant's escape" and blankets that were tied together.

At a press conference yesterday afternoon, Gaston said, "We constantly find ropes; makeshift ropes are a constant problem." He held up such a rope as proof that such items are commonly confiscated.

Less than three months ago, officials found a shotgun, a loaded automatic pistol, shells, wirecutters and hacksaw blades in the jail. At that time, Gaston said the discovery probably had thwarted a planned escape attempt.

The inmates who escaped yesterday were identified as LaRocko Keith Johnson, 26; Robert Lee Rogers, 22; Dominic Ross Henry, 21; Theodore Costello Owens, 36; Harold Dennis Roberts, 27; Andre Phillips, 28; Frank Washington Jr., 28; James Leland Avent, 34, and Labron Rudisill, 30.

All were charged with armed robbery except for Avent, who was charged with violating probation, and Owens, who was charged with manufacturing PCP.

Gaston said the inmates probably had spent several days cutting the window bolts and bar with a hacksaw.

He said the view of guard Robert Smith, who was stationed in a glass booth nearby, was "obstructed by a large structural support column." But after inspecting the scene of the escape with reporters, jail spokesman Jim O'Neill conceded that the column, which is about 15 inches wide, could only block the guard's view if he never moved his sliding chair in the booth, which is about four feet wide.

"That officer doesn't have the visual acuity you do; it's night, it's dark," Gaston said to the reporters after they returned from the inspection. "That guard has to observe both housing sections 3A and 3B. And if he's involved in something, or distracted, nine people can make their egress."

Gaston did not say, however, that any such distraction occurred.

He said Smith, who was not available for comment, told him he "was observing, looking at the individuals. He specifically saw one of them taking a shower at 2:30."

Gaston said marks on two bolts that had been cut indicated a hacksaw had been used to open the third-floor window inside the jail. He said the escapees then cut and removed one of several bars on the outside of the jail window and jumped a few feet onto a jail roof, walked along the roof, and then apparently jumped about 10 feet to the ground and to freedom. Several guards, however, said the prisoners may have lowered themselves on ropes.

Gaston said that while the escape was not detected until around 4:30 a.m., he could not be certain when it happened; he said he only knew that Smith saw one of the inmates taking a shower at 2:30 a.m.

The last time the guards took a count of the inmates was at 11 p.m. Tuesday.

Spokesman O'Neill said jail officials do not plan to take disciplinary action against either of the guards. "Preliminary indications show that there was no negligence," he said.