Authorities investigating a Palm Springs, California, fertility clinic explosion as terrorism

Authorities in Palm Springs are preparing to update the public at a news conference Sunday morning about their investigation into an explosion at a fertility clinic that appeared to have killed the bomber and injured four other people.

The explosion damaged office space, but the clinic's IVF lab and stored embryos were offsite and were not damaged.

Investigators called the explosion on Saturday an "intentional act of terrorism." The suspect posted writings online and attempted to record the explosion, though authorities said the video failed to upload online. An official who was not authorized to discuss details of the attack spoke on condition of anonymity to The Associated Press.

The blast gutted the single-story American Reproductive Centers clinic in upscale Palm Springs, though a doctor told the Associated Press its staff were safe.

"Thank God today happened to be a day that we have no patients," Dr. Maher Abdallah, who leads the clinic, told the in a phone interview.

The person believed responsible for an attack posted rambling online writings before the explosion, according to a law enforcement official.

"Make no mistake: This is an intentional act of terrorism," Akil Davis, the head of the FBI's Los Angeles field office, told an evening news conference.