The condition of a 69-year-old security guard seriously wounded by a gunman during a shooting spree at the IBM Corp. in Bethesda Friday was reported last night to have worsened.

Jessie Roberts Lewis was in the intensive care unit at Suburban Hospital and was listed in very critical condition, according to a hospital bulletin. Lewis had been listed in critical condition.

He was shot three times and suffered a heart attack after the shooting. He was resuscitated but later suffered a second heart attack while in surgery.

Lewis' guard station was in the lobby of the IBM Data Processing building where Edward Thomas Mann, the 38-year-old suspect in the attack, rammed his car through the doors in the shooting that left two dead and seven wounded. Mann, of Mitchellville in Prince George's County, has been charged with murder and is being held in Rockville.

The conditions of several other wounded victims had improved by last night. Warren E. Winnie III, 37, of Harper's Ferry, W. Va., was taken off the critical list and was reported in satisfactory condition with a bullet wound in the abdomen. Charles Dickerson, 27, of Silver Spring, had gone from critical to satisfactory condition but was still in the intensive care unit recovering from multiple gunshot wounds. Kenneth Tutwiler, 61, of Rockville, was in stable condition in the hospital's coronary unit. He suffered a heart attack during the attack but was not shot.

The conditions of Carl Kreutzberg, 44, of Chevy Chase and John O'Leary, 48, of Herndon, both of whom suffered multiple gunshot wounds, remained unchanged. Kreutzberg was in satisfactory condition and O'Leary was still listed as critical and in intensive care.

Police continued to comb the building for more evidence about the shooting spree, which began shortly before 11 a.m. last Friday. IBM employes who escaped during the 7 1/2-hour seige returned to the site and were escorted by police, in groups of three, into their offices to collect personal belongings they had left when the shootings began.