An employee of a pizzeria in San Francisco's Nob Hill neighborhood was stabbed to death early Tuesday morning while on a break.
The stabbing happened outside Bellissimo Pizza on Sutter Street shortly after 1:30 a.m.
The victim, whose name has not been released, was taken to San Francisco General Hospital, where he died.
The motive for the attack remains under investigation, but Police Sgt. Wilfred Williams said it does not appear the employee and the suspect knew each other. He said the alleged attacker had asked the employee for water a few minutes before he was stabbed.
The Chronicle reported the victim gave the woman the water. She left with her drink only to return a few minutes later armed with a knife.
After the attack, Williams said, Achekzai ran away and witnesses to the stabbing followed her. She flagged down a passing motorist and asked for a ride, telling the driver she was being threatened, Williams said.
The car didn't make it far before police responding to the initial call pulled it over and took Achekzai into custody, Williams said.
Police have recovered what they believe is the murder weapon.
Bay City News contributed to this report.