(SANTA MARIA, Calif.) -- A man allegedly threw an explosive device inside a California courthouse on Wednesday, injuring five people, the same day he was set to be arraigned on firearms violations, authorities said.
The explosion was reported around 8:48 a.m. PT Wednesday at the Santa Maria Courthouse in Santa Barbara County.
The suspect allegedly lunged through the courthouse doors and tossed a small bag past the weapons screening station, and the bag exploded as it hit the floor outside of the local arraignment room, Darrel Parker, the court executive officer, told ABC News.
Five people suffered non-life-threatening injuries from the explosion, including burns, according to Santa Barbara County Sheriff's Office Undersheriff Craig Bonner.
The suspect, identified by the sheriff's office as 20-year-old Nathaniel McGuire, will be booked on multiple local charges, including attempted murder, using an explosive device and attempting to kill someone, and possession of explosive devices, Bonner said. He will be held without bail, Bonner said.
Authorities believe the explosion was the result of an "intentionally set improvised explosive device," Santa Barbara County Sheriff public information officer Raquel Zick wrote on social media.
The suspect was detained as he attempted to enter his car outside the courthouse, Bonner said. He was wearing body armor under his jacket, according to Bonner. He also allegedly had weapons and ammunition in his car, Parker said.
The suspect's alleged motivation in the explosion "appeared to have stemmed from a recent arrest" by the sheriff's office, Bonner said during a press briefing Wednesday evening.
In that case, McGuire was arrested for firearms violations on July 28, Bonner said. Deputies had seized a "loaded and concealed revolver that was in McGuire's pants pocket and was not registered to him," Bonner said.
He was set to be arraigned in that case Wednesday morning, Bonner said. Court records show his arraignment was scheduled for 8:30 a.m. PT at the Santa Maria Courthouse on a charge of carrying a loaded firearm. An attorney for McGuire was not listed in that case.
Detectives are working with Santa Barbara County Fire to see if the suspect is associated with several recent additional arson fires, Bonner said.
Authorities do not believe there are any additional safety concerns at this time, Bonner said.
The FBI is also investigating the incident. The suspect has no known ties to terrorism, authorities said.
Five people were injured in the explosion, Bonner said. They have all since been treated and released from a local hospital, he said. The victims were all civilians, with no court employees among those injured, Parker said.
The courthouse will remain closed on Thursday amid the investigation.
"We will thoroughly review this incident to make sure that we could take whatever steps are necessary to reduce the chance of this ever happening again in the court," Parker said during the press briefing.