ALBANY, Ga. (AP) _ A registered nurse was indicted Tuesday on six counts of murder and 20 counts of aggravated assault in the poisoning of surgery patients under her care, including a 3-year-old child.

The indictment, returned by the Dougherty County grand jury, accused 24- year-old Terri Rachals of injecting 11 patients in Phoebe Putney Hospital's surgical intensive care unit with potassium chloride, causing six deaths.

Two of the others also have died, but Mrs. Rachals was not charged with directly causing their deaths.

The nurse, who had worked at the south Georgia hospital for six years, was arrested March 14 on a charge of murdering Andrew Daniels, 73, a retired construction worker from Moultrie who was recovering from a hernia operation.

Authorities said potassium chloride was injected into the intravenous apparatus with which Daniels was being treated.

An investigation began after nine cardiac arrests occurred in the surgical intensive care unit during the first three weeks of November. There usually are three or four per month.

Potassium levels in the bodies of some of those who died were abnormally high, arousing suspicions, officials said. Potassium chloride is widely used in surgery in small, diluted amounts, to regulate the heart but is lethal in large doses.

Tuesday's indictment charged Mrs. Rachals with murdering Daniels; Minnie Houck, 58, of Moultrie; Milton Lucas, 68, of Sylvester; Norris Morgan, 3, of Albany; Roger Parker, 36, of Ashburn; and Joe L. Irvin, 36, of Albany. All died between Aug. 19 and Nov. 26, 1985.

In addition, she was charged with 20 counts of aggravated assault on nine patients, many of whom received more than one injection, the indictment said.

Mrs. Rachals, who is undergoing psychiatric evaluation at Southwestern State Hospital in Thomasville, is the mother of a 2-year-old boy. Mrs. Rachals is no longer employed by the hospital, Phoebe Putney Administrator Duncan Moore said Tuesday.

Investigators have declined to speculate on a motive. ''We're still investigating the case,'' District Attorney Hobart Hind said Tuesday.

In another development Tuesday, the Georgia Board of Nursing suspended Mrs. Rachals' nursing license and scheduled a hearing March 31.

The suspension order said the board had determined that continuing her license to practice posed ''a threat to the public health, safety and welfare.''