Two convicted armed robbers who escaped Sunday afternoon from the Upper Marlboro jail remained at large last night, the Prince George's County Sheriff reported.

Sheriff Don Edward Ansell said the two escapees were spotted by citizens between 8 and 9 a.m. yesterday in a wooded area around Upper Marlboro. He would not specify the location of sighting but said deputies and county police searched a wooded area that lies within a two-to 10-mile radius of Upper Marlboro.

A dense fog yesterday morning apparently helped the convicts hide from searchers.

Kevin Gill, 17, convicted of breaking and entering and armed robbery, and Richard Dean, 24, also convicted of armed robbery, escaped about 4:30 p.m. Sunday after they apparently ripped off a piece of plywood covering a window in the jail's weight-lifting room, then squeezed through a six-inch space between the bars.

Both Gill and Dean were awaiting placement in a state penal institution. Gill was sentenced to 15 years on the breaking and entering charge and 18 years on the armed robbery charge. Dean was serving a 20-year sentence.

Ansell said two other inmates alleged to have assisted the two escapees have been charged with conspiracy to commit escape and attempted escape. Charged were Robert Thompson, 23, of Forestville. Serving a 10-year sentence for rape, and William Brook, 32, of Washington, serving 20 years for armed robbery.

Ansell said there was no one else in the weightlifting room when the inmates escaped. He said four deputies were on duty at the jail at the time and were responsible for about 160 inmates.

Ansell blamed the escapees "lack of personnel."

He also said the two escapes probably were injured when they slid through the iron bars, which he said were rectangular and had sharp edges. Both escapees, he said, were small, slim men but still "would have had a hard time" slipping through the bars. Ansell said he has asked the County Public Works Department to replace the bars on the weightlifting room window with ones only four inches apart.

Sgt. William Graham said deputies were stopping and searching cars in Upper Marlboro yesterday morning and that 30 deputies were on the lookout for the escapees in roving patrol cars. Graham said the country canine squad also is assisting in the search.