A cafeteria worker at the National Institutes of Health was killed and a second was injured in an electrical accident during lunch hour yesterday in front of hundreds of diners in a crowded cafeteria on the NIH campus in Bethesda.

Shirley Foster, of 823 Bellevue SE, Washington, was electrocuted when she leaned over and touched a yogurt machine that apparently had short-circuited in the cafeteria line at NIH's clinical center, according to NIH officials.

A second worker, identified by Suburban Hospital as Lilly Crawford, 33, of Silver Spring, was injured seconds earlier when she touched the machine while serving frozen yogurt and then collapsed, according to Dr. Edwin Becker, director of research services at NIH. Crawford was treated for an electrical injury to her arms and admitted in stable condition to Suburban, according to a hospital spokesman.

According to Becker, a "surge of electricity" went through Foster's body when she leaned over the machine, apparently to help her co-worker, seconds after Crawford collapsed. Foster's body "was frozen onto the machine" until another cafeteria employe kicked the machine away from her body, Becker said.

Charles Johannsen, of Woodbridge, who was in the crowd of diners, said he suddenly "heard squealing and everybody started crowding around" the counter where the incident occurred. He said that he yelled for doctors to assist the injured women and two immediately responded.

The cafeteria is operated by Guest Services Inc., which runs a number of government cafeterias in the Washington area, according to Becker. James Pflaging, GSI's vice president of marketing and development, said that Foster was in her 40s and had worked for GSI for about three years.

Becker said that the first woman was injured when she was operating the machine and a short circuit apparently caused the metal case of the machine to become "electrically hot." She was shocked by the electricity and collapsed, he said.

Then, the second woman, Foster, leaned over the machine. Her upper body came in contact with the "electrically hot" metal case, while her leg touched a safe used to hold the cafeteria receipts, according to Becker. The electricity then surged through her body.

Becker said two electrical malfunctions must have occurred in the yogurt machine to cause the problem. The grounding wire in the machine's motor must have been loose so the metal case was not properly grounded, he said. At the same time, a short circuit within the machine must have occurred, he said.

Becker said an NIH cardiac arrest team of two doctors and three nurses attempted to revive Foster, who was then taken to the intensive care unit at the clinical center, which is a research hospital.