Transcript for Deadly explosion at California day spa wasn't an accident, officials say
And tonight, to the deadly explosion inside a building in southern California. Authorities revealing a woman was killed by what appears to be a package that blew up. The chaotic scene. The FBI on the scene again tonight. A nearby daycare evacuated. The children holding hands. ABC's kayna Whitworth with what authorities revealed late today. Reporter: Tonight, authorities saying the deadly explosion that rocked a southern California community, killing a 40-year-old woman, was no accident. Sheriff's officials say it's possible ildiko krajnyak, the owner of the day spa, may have been targeted. Investigators are still working to confirm whether or not this was an intentional act. At this point, our working theory is this explosion was caused by a device. Reporter: Sources say preliminary indicators are that the division was inside a package that was dropped off at the business. At this time, we do not know how the device arrived at the location. Reporter: The blast, killing her and injuring three others. 100 children, including babies still in cribs, evacuated from a daycare and school across the street. The extent of the damage seen here. The foe toeps from inside the building. Today, investigators were seen removing boxes of evidence from the victim's home. The associated press reporting she was separated, but still living there with her husband. And kayna with us again tonight. And kayna, authorities trying to calm the public, because you told us they do not believe there's a possibility of any other devices at this point? Reporter: Right, David. So, authorities saying tonight, they don't see any additional threat to the public, and found no evidence of more targets. David? That is reassuring. Kayna, thank you again tonight.
This transcript has been automatically generated and may not be 100% accurate.