A concrete block wall yesterday collasped in a one-year-old record distribution warehouse in Howard county, injuring six employes, one critically, police said.

Howard County police said 28 people were working in the packaging division of the Handleman Company near Laurel at 1:30 p.m. when a concrete block wall 50 feet wide by 18 feet high caved in.

Piyu Thomas, 27, of the Fort Meade area, was taken by helicopter to the Shock Trauma Center at the University of Maryland where she was treated for a fractured pelvis and thigh as well as facial cuts, hospital officials said.

An injured woman employe was taken to Greater Laurel Hospital, where she was listed last night in stable condition. The remaining four injured empolyes were taken to Howard County General Hospital, where one was admitted for observation and the others released.

Police officials said the Handleman Co. lease the building. According to Robert Gemmill, chief of the county's Bureau of Inspection and Permits, the building is owned by Prudential Insurance Co.

"The building was basically a large warehouse divided into several occupancies," said Richard Freas, a member of Howard County's Savage Volunteer Fire Department, who was called to the accident scene.

He said that one of the dividing walls "apparently just collapsed very suddenly . . . apparently there was not much warning."

Breaking the fall of the masonry-and possibly preventing more worker injuries-were a number of six-to-seven-foot, freestanding metal shelves, Freas said. The shelves, which were packed with records and tapes apparently intended for packing and distribution, were hit first, he said.

Freas said the stunned employes were quiet and "pretty orderly" as firemen worked to evacuate the injured.

Shortly, after the firemen arrived, he said, building inspectors from both the county and state occupational safety and health administration arrived at the scene.