An inmate escaped from the Prince George's County Detention Center in Upper Marlboro last night, and three others failed to reach freedom in the third bid to flee from the new facility, which has been described as "state of the art."

Corrections officials said two of the three who failed to reach the outer perimeter fence of the six-month-old jail were injured -- apparently cut attempting to scramble over an outer-perimeter fence, which is topped with razor-sharp wire.

The injured were taken to Prince George's Hospital Center, where their injuries were described as lacerations.

The escapee was identified as Michael Mac Thompson, 24, of Landover.

A Corrections Department spokeswoman said Thompson had been jailed on robbery and house-breaking charges.

Four men had climbed a brick wall in the courtyard about 10 p.m. to reach and somehow break through a covering of chain-link fencing, jail officials said, but Thompson was the only one able to race to and scale the outer fence.

A new underground sensor -- installed after two escapes -- alerted guards who apprehended the other three, Corrections Department spokewoman Christy Merenda said.

The three whose escape bids were foiled were identified early today as Leonard Sylvanius Jordan, Samuel William Brown and Larry James Simpson. The two taken to the hospital were Jordan and Simpson.

Further information about them was not available early today.

The two previous escapes from the $43 million jail, which opened Feb. 28, proved embarrassing to corrections officials who had described the facility in glowing terms.

Two male inmates climbed over two razor-wire-topped fences May 26 and escaped into a wooded area. Corrections officials said at the time that a guard assigned to patrol the prison grounds that night had been called to a hospital, leaving the area unmonitored.

The two escapees were later caught.

In the second escape, a 22-year-old woman who had been extradited from the District of Columbia was able to talk her way onto a bus designated for inmates in the Corrections Department's weekend work program upon her arrival at the county jail on the evening of June 6.

She fled the bus when the driver allowed her to leave to use a restroom, but she was apprehended about five hours later in Southeast Washington.

The Corrections Department added 14 guards to the jail's staff June 22. At that time, the Corrections Department head, Samuel F. Saxton, submitted his resignation after public criticism of understaffing and a mandatory overtime policy for guards at the jail. Saxton later withdrew his resignation.

Fifteen additional guards were assigned there July 6 after more criticism of the prison fostered by the successful escapes.

Previously, county Sheriff's Department deputies had patrolled the perimeter of the jail for the Corrections Department between 3 and 11 p.m.

Now, 205 guards are assigned to the jail, enabling the department to staff its own perimeter patrols.

Spokeswoman Merenda said corrections officials are still planning to install supposedly unclimbable mesh over fences at the facility and and to develop a dog unit. Staff writer Douglas Stevenson contributed to this report.