Police say Richard Starry fatally shot himself inside the Retama Manor nursing home in Robstown, Texas, after killing his father and stepmother

South Texas police continue to investigate a deadly shooting spree on Friday night apparently carried out by a 60-year-old man who killed himself inside a nursing home after killing four relatives — including his dad and stepmom and the 13-year-old boy they had adopted, PEOPLE confirms.

A motive remains unclear as detectives continue to probe what may have driven Richard Starry’s suspected actions.

At a news conference held over the weekend, authorities said they believe Starry fatally shot himself inside the Retama Manor nursing home in Robstown after gunning down his 85-year-old father, Ernest Starry, and his stepmother, 60-year-old Thelma Montalvo.

Robstown Police Lt. Enrique Paredez told reporters that officers responded to an “active shooter” at the nursing home shortly after 7 p.m. Friday, where they found the three bodies.

Credit: Monica Lopez/Caller-Times

As authorities were processing that crime scene, a second call was made to 911 from an unnamed family member who was concerned about Montalvo’s 41-year-old son and the couple’s teenage son.

Police respond to the scene of Friday’s murder-suicide
| Credit: Alexandria Rodriguez/Caller-Times

Officers arrived at the home Richard shared with both Montalvo’s adult son and her 13-year-old with Ernest and found their bodies.

The sons, too, had been shot to death. Their names have not been released.

All five deaths are being investigated as a murder-suicide, officials said.

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The boy was an active Boy Scout, according to the Corpus Christi Caller-Times.

“He was known very well by our scout family,” a local reverend told the paper. “They’re stunned and devastated by this, particularly the scout leaders. They knew him well.”

Police remain at the scene
| Credit: Alexandria Rodriguez/Caller-Times

“Our hearts go out to the victims’ families and the residents, visitors and employees at Retama Manor who experienced this tragedy,” Robstown Police Chief Erasmo Flores said in a news release.

PEOPLE’s calls to the nursing home were not immediately returned on Monday.