A bomb explosion outside a California fertility clinic has killed one person and injured four others in an “intentional act of terrorism”, FBI officials have said.

The blast happened just before 11:00 local time (19:00 BST) less than a mile from downtown Palm Springs, near several businesses including the American Reproductive Centers (ARC). The clinic said no-one from the facility was harmed.

The suspect in the blast has been identified as 25-year-old Guy Edward Bartkus, according to sources familiar with the investigation who spoke to BBC’s US partner CBS News.

Witnesses told the BBC the blast was strong enough to shatter windows and badly damage a nearby building that housed the ARC.

Michael Beaumier, a witness, said he was knocked off his bike by the blast. “It was that big of an explosion and I could hear windows shattering all around me,” he said.

Rhino Williams, who was at his restaurant nearby, told the BBC he initially thought the explosion was a plane or helicopter crashing.

He said he ran to the scene to see if he could help, finding a badly damaged building with walls blown out and the front axle of a car on fire in the car park.

“That’s all that was left of it,” Mr Williams said. He also saw an iPhone on a tripod still standing in the car park, as if it was set to film or stream the explosion.