A man has been arrested after an explosion at a department store in California.
Hugo Gonzalez, 49, was behind the blast at a branch of Sam's Club, a membership-only warehouse chain owned by Walmart, police said..
The incident in the city of Ontario sparked a major response with fire, police and ambulance rushing to the scene.
There were no injuries reported.
Police were initially called to what was believed to be a fire at around 2pm on Thursday.
But witnesses reported hearing a "popping sound" and cops said they discovered a "small explosive device" had been detonated in the store.
"There appears to be no structural damage or any injuries at this point. All employees and customers are accounted for," police tweeted.