Authorities in California have a suspect in custody after an explosive device detonated inside of a Sam's Club in California on Thursday afternoon.

Hugo Gonzalez, 49, of Fontana, was identified as the man suspected of detonating the device, the Ontario Police Department tweeted, noting it's believed he acted alone and a motive remains unclear.

Law enforcement was dispatched to the Sam's Club store in Ontario after it was reported around 2 p.m. that someone heard a "popping sound," KABC reported.

"Responded to a possible fire structure at [Sam's Club]," the Ontario Police Department tweeted earlier Thursday. "It has been determined the suspect detonated a small explosive device in the store."

A follow-up tweet stated, "There appears to be no structural damage or any injuries at this point," and noted that "All employees and customers are accounted for."

Miles from the store, Gonzalez was pulled over and detained, police said. Within his car, investigators found "[additional] materials" that were "similar to those used in the devices" found inside Sam's Club.

Police are now investigating an apartment in Fontana, "which is believed to be associated w/Gonzalez."

Gonzalez is currently in police custody and is being interviewed by investigators.