A man suspected of attacking two women, including stabbing and killing an 18-year-old victim Nia Wilson, at the MacArthur BART station in Oakland on Sunday has been arrested thanks to, in part, a vigilant resident who called the police on the suspect when she spotted him Monday.
Bri Spearman was one of several people who alerted law enforcement officials to John Lee Cowell's whereabouts when she saw two young men chased Cowell onto a BART train at the 12th Street Oakland City Center station.
Spearman was commuting home from San Francisco when Cowell got on the train and brushed up against her. She recalled getting nervous after seeing him, taking a seat and pulling up the photo of a man suspected of stabbing Wilson and her sister.
"Honestly I was scared. His attack on Nia was unprovoked. He was very fixated on me and another young African American lady that was on the train," Spearman told NBC Bay Area.
She said he had his hands in his boxers and she was worried he might pull out a weapon.
"I just wanted to watch his hands and watch him and keep my eyes on him. I didn't want to be the next victim. I didn't want her to be the next victim. It was frightening," Spearman recalled.
BART police arrested the 27-year-old suspect without incident at the Pleasant Hill station. Cowell was then detained and taken to the BART police station at Lake Merritt in Oakland for questioning.
A video of the arrest, recorded by Spearman, showed officers putting handcuffs on Cowell, calling on their radio and calmly speaking with the suspect.
Spearman said she was surprised by how smooth everything went down. The police didn't act like the man was armed and dangerous, she said.
"I think the Bay Area community helped. Not just me; we all helped catch this guy," Spearman said, referring to other tips police received before Cowell was eventually apprehended.
"I’m relieved he’s caught. We still don’t know his motive. It’s still uneasy for me and a lot of African American women," she said.
Surveillance video on the train and at the station's platform showed Cowell had been riding the same car as the sisters Sunday, but they did not interact, Police Chief Carlos Rojas said.
A motive for the attack remained unclear. Rojas said Cowell hasn't been connected to any radical or white supremacist groups, although he added: "We are going to explore all options and all possibilities."
Over 1,000 people attended a vigil for Wilson Monday evening at the MacArthur BART station. Her death was the third involving an attack in the BART system in five days, making it one of the deadliest weeks in the system's history.
Ansar Mohammed, the father of the victims, spoke out after the attack, calling it "a parent's worst nightmare."
"I never imagined myself going through nothing like this," Mohammed said. "That's my baby girl laying up there. I want justice for my daughter."
The Associated Press contributed to this report.