OXNARD (CBSLA.com) — Dramatic video has been released of a man who police say stands accused of building a chemical weapon inside a Walmart store in Oxnard.

The man wearing all black is initially seen in the security footage from June 18 blending in like any other shopper.

But, authorities say, he didn’t come to the store to shop, but to build a chemical weapon.

“This is a very bizarre case,” said Eric Sonstegard, the Oxnard assistant police chief.

Detectives identified the suspect as Martin Reyes. They say he went to the store after conducting research online on how to build a deadly chemical weapon.

Once inside the store, police said the man assembled all of the ingredients from store shelves, which included some kind of electronic appliance.

Police said he used a socket near the stationary section to plug in the appliance, which was then designed to set the chemical weapon off.

“This device could have caused a lot of harm,” Sonstegard said.

Store employees noticed Reyes, and the weapon and called 911. Everyone inside the store was evacuated.

Customers who are just now learning about the incident are shaken.

“It’s scary. This is only my second time at this Walmart. And with what’s happening today, it’s scary,” said Yvonne Railey, a shopper.

“I would have freaked out. But it doesn’t surprise me,” said another shopper.

Oxnard detectives utilizing evidence at the scene and security video tracked down Reyes Tuesday. He was already behind bars on unrelated charges.

“He ended up admitting the entire thing and basically telling them how he created the device,” Sonstegard said.

Police said the suspect is mentally unstable and described him as a “career criminal.”

A motive for the incident is unknown.