SAN JOSE, Calif. (KGO) — San Jose police officers shot and killed a man armed with a knife at a public park Sunday afternoon after he allegedly stabbed his own son to death.

It is the second shooting involving an officer in a one week time period.

It all started with a hysterical call from a father to help his nine-year-old son who was stabbed in North San Jose.

What police didn’t know at the time, was the man who made the call was also the person who committed the crime.

“The officers who responded that afternoon were running toward what they believed was a child desperately in need of help,” SJPD Chief Paul Joseph said. “They came intending to save a life, not to take one. They had no idea of knowing that this horrific and unfathomable act of violence had already to the loss of an innocent child’s life before they even arrived.”

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On Monday, San Jose Police Chief Paul Joseph detailed what led to the death of a child and the shooting of Mateusz Dzierbun by police.

Joseph said around 3:50 p.m., police responded to the park when they found Dzierbun standing over his own son covered with blood and holding a knife.

“A deranged man who had murdered his own son,” Joseph said. “His call for help was actually a twisted plan to force officers to shoot him. It was a final, desperate and selfish act – suicide by cop.”

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Police say the 48-year-old Fremont resident described the suspect on the 911 call as if it were a different person, when in fact it was his own description.

Joseph said it was unknown to SJPD that Dzierbun had any criminal, mental health or child welfare history.

Officers attempted to get Dzierbun to drop the weapon so they could provide aid to the child.

That’s when he charged the officers with the knife, before being shot by an officer and a sergeant.

“What we do know is the conclusion of this tragedy was both deliberate and calculated,” Joseph said. “The suspect chose the location and pre-planned a confrontation with officers in order to force them to take his life.”

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Back at the park Monday, it was business as usual.

Residents we spoke with could not believe something like this had happened just the night before.

“Been a police officer for 33 years, I don’t ever remember a parent murdering their child so brutally,” Joseph said. “I don’t remember a lot of homicides as violent and as brutal as this one.”

An investigation into the homicide, as well as the officer involved shooting, is now underway following this horrific tragedy.