Chinatown residents are unnerved by a seemingly random attack in which a man waiting to cross the street was randomly and violently stabbed in the back by another man who said nothing and proceeded on his way.

From the looks of the March 5 attack, which was caught on surveillance video that was quickly shared with the media, the suspect appeared to specifically target the victim, approaching on the sidewalk from behind, aggressively thrusting a weapon into his back, and then strolling on across the street with a plastic shopping back in his hand.

The attack happened at the intersection of Stockton and Sacramento streets.

A witness has since come forward saying that the suspect, 37-year-old Jian Feng Huang, had just been eating in a restaurant down the street before walking, perhaps with leftovers in that plastic bag, down the sidewalk and stabbing the victim.

The victim could be seen in the video — it's here on YouTube and not embeddable because it is age-restricted — grabbing his back and then falling to his knees and collapsing on the ground.

As ABC 7 reports via court documents, the knife only narrowly missed the victim's aorta, and he was put into a medically induced coma.

Prosecutors now say that Huang "acted without mercy and with the specific intent to kill the victim," though investigators have said that the suspect and victim did not appear to know one another.  As prosecutors said in court documents, the act occurred with "no words spoken, no threat posed."

Huang was apprehended shortly after the stabbing about five blocks away, on the 600 block of Powell Street, on Nob Hill.

ABC 7 spoke to people in Chinatown who said they knew Huang's father.

Huang has a previous conviction for arson in 2020, in San Mateo County.

Huang has been charged with attempted murder and several other charges. He pleaded no guilty in court Tuesday.

Previously: Stabbing In Broad Daylight In SF's Chinatown Leaves One Man Critically Injured