Investigators are combing through the writings of a 25-year-old man believed responsible for an explosion that ripped through a Southern California fertility clinic over the weekend.

One person was killed and at least four other people were injured in a vehicle explosion outside of a fertility clinic in Palm Springs in what the FBI called an "intentional act of terrorism."

Five people were killed on Saturday when two helicopters collided and crashed in a wooded area near Eura Airport in southwestern Finland, police said.