The car bombing outside a California fertility clinic that killed one person and injured four others appears to have been driven by anti-natalist ideology, according to two senior law enforcement officials briefed on the incident.

Authorities are investigating what appear to be radical views that Guy Edward Bartkus expressed online in the months before Saturday’s attack.

The blast on Saturday in Palm Springs, California, injured four people and severely damaged several buildings, authorities said.

At a press conference, Akil Davis, FBI assistant director in charge of the Los Angeles field office, said the bombing was “an intentional act of terrorism.”