A Filipino man shot and killed his wife and grandson on Thursday before killing himself while visiting the pair at a mental health center in Mandaluyong City, the Philippines.

At 2 pm on Thursday at the National Center for Mental Health (NCMH), the 80-year-old man and his wife, 78, went to visit their grandson, 27, a patient in the institution. The man suddenly pulled out a gun and shot his grandson first, then his wife, Rappler reported.

The man then shot himself in the head. According to Colonel Moises Villaceran Jr, the Mandaluyong police chief, the three were arguing when the incident happened. The man and his grandson died on the spot, while the woman was taken to a hospital but was later pronounced dead after undergoing emergency treatment.

Villaceran said the man was a frequent visitor to the center, which helped him gain the trust of the center’s personnel, and he managed to hide the gun in a brown envelope. Villaceran added that the father of the patient had earlier warned hospital personnel not to allow the grandfather inside the institution.

The Department of Health (DOH) said in a statement that the Philippine National Police was investigating the case in cooperation with the NCMH. The DOH said there were no other patients or NCMH staff hurt or involved in the incident and that the hospital is in full operation and functioning normally.

“Due to the sensitivities of the issue involving the patient, we ask for privacy for the bereaved family,” the DOH said.