A staff member at a dementia care facility in Diamond Bar was arrested Saturday on suspicion of killing two elderly women under his care, authorities said.

Sheriff’s deputies were called around 8 a.m. to the Happy Home Care for Elderly, an assisted-living facility located in a four-bedroom suburban home, according to Lt. Daniel Vizcarra.

Two “extremely elderly women … were found in a room within the house,” Vizcarra said. Paramedics came and attempted to provide aid, but both women died at the scene.

Detectives did not disclose the identity and age of either victim. Their manner of death was under investigation by the L.A. County Medical Examiner-Coroner, but Vizcarra dismissed online reports of a shooting. “Nobody was shot,” he said.

The live-in caretaker, Jianchun Li, was arrested Saturday afternoon and booked on suspicion of killing both women. Li, 40, was being held in county jail in lieu of $4-million bond, according to booking records. He is scheduled to appear in the Pomona Courthouse on Tuesday.

The Happy Home Care for Elderly, a state-licensed residential care facility, touts its “homelike environment” and “well-trained staff to look after your loved ones,” according to its website. The home has space for up to six residents, according to state records; four other residents at the home were not harmed, Vizcarra said.

The slayings were a shock to the quiet San Gabriel Valley neighborhood.

“We would never have thought something like this could occur,” Ivonne Trypucko, the manager of a swim club across the street from the elder care home, told KTLA.