WASHINGTON (AP) _ A handgun-safety group on Sunday urged parents to take precautions to keep handguns away from their children, especially at this time of year when children are off from school.

The Center to Prevent Handgun Violence, a non-profit group established in 1983 to educate Americans about the risks of handgun ownership, released a study that found that 38 percent of the unintentional shootings of children were either self-inflicted or inflicted by other children.

The study, called ''Child's Play: A Study of 266 Unintentional Handgun Shootings,'' also found that an additional 41 percent of the guns used in shootings of children were owned by a friend's parents or by relatives other than the victim's parents.

The center studied 266 unintentional shootings of children that took place between January 1986 and May 1988. The shootings were either self-inflicted or inflicted by other children age 16 and under. The center said it compiled its data from reports in the news media and, in some cases, follow-up conversations with police departments and hospitals.

Peter Shields, chairman of the center, recommended that parents either remove handguns from their homes or, ''at the very least, keep them unloaded and securely locked up.''

Shields also suggested that parents check with adults at other places where their children play to make sure that loaded guns are not easily accessible.

He added that children may be at particular risk of unintentional shooting during the summer because ''children aren't in school and have more free time. They'll be spending more time playing at their homes and those of friends and relatives.''