Pennsylvania authorities are investigating a possible nursing home murder-suicide following the death of a resident and registered nurse, ABC News reported.

Officials allege a 42-year-old nurse arrived to work at Abington Manor on Monday night with a semi-automatic handgun, shot a 79-year-old patient and then committed suicide around 5:30 p.m., according to Police Chief Robert Gerrity.

The names of the nurse and patient have not been released as authorities are still notifiying their families. 

Police have not suggested a motive at this point. The nurse was employed at the nursing home since 2011 and the patient had lived there for about two years. 

According to The Times-Tribune, employees at the nursing home said there was no indication of the nurse being upset or angry. 

"The unknown is motive," Gerrity said. "What caused the person to act in this manner? What reasons, what relationship there was between this resident and the staff employee, we just don't know, and we may never know." 

Jeanne Moore, an Abington Manor spokeswoman, released a statement regarding the alleged murder-suicide.

"We were shocked by the tragedy that occurred at the center this evening," the statement read. "We are cooperating fully with law enforcement officials at this time and are hopeful that their efforts will help us to understand this tragedy. We are focused on the well being of our patients, residents and staff and cannot comment further at this time." 

Gerrity emphasized that all other residents in the home are safe.

"Nobody else is in danger," he said. "This is an isolated incident." 

He also thanked the staff for being helpful during such a tragic situation.

"The staff is wonderful," Gerrity said. "They've been giving aid and comfort to the residents here, and I think they did a marvelous job keeping everyone under control."