SUNNYVALE, Calif. (KTVU) – A man armed with a knife was fatally shot by Sunnyvale Department of Public Safety officers Wednesday as he attempted to rob a liquor store, authorities said.

The incident happened just before lunchtime in a busy strip mall at Tasman Drive near the Lawrence Expressway.

Investigators in Sunnyvale said in the moments after an armed robbery at this liquor store, an officer found the suspect in a back alleyway.

Police scanners captured what happened next.

"Take your hand out of your pocket," the officer can be heard saying.

Then minutes later, "He's refusing to comply, he has the knife. He's about 50 feet away, he's standing still."

Then the officer says, "He's walking towards me. Put the knife down!"

And finally: "Shots fired. Suspect is down."

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Witness Alvaro Camilo was on his lunch break when he saw the shooting happen.

"The guy was just standing, standing holding a knife. And we just heard the officer screaming at him, put the knife down cause he wouldn't listen. He went towards him with the knife. That's when they shot him," said Camilo.

"By the time we went back out there, after the shots were done, went out there and saw police on top of the suspect and he already looked gone," said Dave Palmer, another witness.

The suspect, a white male in his mid-20s, was transported to the hospital, where he was pronounced dead.

Investigators recovered the knife at the scene.

"We always conduct a thorough investigation any time we have an officer involved incident. So that's always been our practice and continues to be our practice," said Deputy Chief Dave Pitts of the Sunnyvale Department of Public Safety.

Camilo told he recorded the whole thing on his cell phone, but police took it.

"Yeah we have a video but they needed it for their investigations," says Camilo.

Authorities said they'll review it, along with any video that may come from inside the liquor store.

"With any investigation we want the truth. So if video evidence helps us get to the truth in exactly what occured, that's a good thing," says Deputy Chief Pitts.

The officer has been placed on routine paid administrative leave. Both Sunnyvale and the Santa Clara County District Attorney's Office will conduct investigations.