PORTLAND, Ore. >> An Oregon hospital is acknowledging that it administered the wrong medication to a patient, causing her death.

Loretta Macpherson died Wednesday, two days after she was given a paralyzing agent typically used during surgeries instead of an anti-seizure medication, said Michel Boileau, chief clinical officer for St. Charles Health System. The error occurred at the organization’s hospital in Bend.

“Tragically, there was a medication error made,” Boileau said.

Macpherson, 65, stopped breathing and suffered cardiac arrest and brain damage after the drug was administered Monday in the hospital’s emergency room, Boileau said. She had come into the ER with medication dosage questions after a recent brain surgery.

The paralyzing agent, rocuronium, is often administered to patients in the operating room while they are attached to a ventilator, Boileau said. Used in this way, he said, it’s a safe medication.

The drug the patient was supposed to receive is called fosphenytoin, health system spokeswoman Lisa Goodman said.

The health system doesn’t yet know how the error occurred, Boileau said Thursday. The investigation is looking at every step of the medication process: from how the medication was ordered from the manufacturer, to how the pharmacy mixed, packaged and labeled the drug, to how it was brought to the nurses and administered to the patient.

“We’re looking for any gaps or weaknesses in the process, or to see if there has been any human error involved,” Boileau said.

Three employees involved in the error have been placed on paid administrative leave.

Boileau did not say how the hospital figured out what drug was wrongly administered to Macpherson. He said the hospital is analyzing the patient’s blood samples to confirm the initial findings.

The hospital also notified the Deschutes County district attorney, who did not immediately return a call for comment. But “there is no suggestion or thought of any kind of criminal activity,” Boileau said, adding that the St. Charles Health System has not seen a similar situation in his 28 years with the organization.

Macpherson, a resident of the small central Oregon town of Sisters, is survived by two sons, Mark and Pete. They had called KTVZ-TV to bring the hospital’s error to light, and the station was the first to report on it Wednesday evening.

“She was a beautiful soul,” Mark Macpherson said. “Everyone she encountered, she’d ask a million questions to get to know you. She was a people person and she loved everybody.”

Boileau said the hospital staff also is reeling.

“For something like this to happen,” he said, “it’s devastating for her family, but it’s also devastating for the hospital staff who are involved in this. People who go into health care never intend to harm someone.”

Studies show hundreds of thousands of people die every year across the U.S. due to hospital errors. A 1999 report from the Institute of Medicine put the number at 98,000 people a year. A more recent report published in the Journal of Patient Safety last year says the number is likely much higher: from 210,000 to 400,000 people annually.

The studies don’t specify the percentage of deaths caused by medication-related errors.