Oakland, CA – Protesters threw explosives at police Tuesday night, following the arrest of the man who fatally stabbed one woman, and wounded her sister, on a train platform in Oakland on Sunday night.

“In my close to 30 years of police experience, it was probably one of the most vicious attacks that I’ve seen,” Bay Area Rapid Transit (BART) Police Chief Carlos Rojas said of the stabbing during a press conference on Monday, according to the San Francisco Gate.

Nia Wilson, 18, and her 26-year-old sister Lahtifa were transferring trains on the MacArthur platform at about 9:36 p.m. on July 22 when they were approached by a man with a knife.

Police said John Lee Cowell, 27, stabbed both sisters in their necks, and then fled through the parking lot of the train station.

Police have not yet found any evidence that the attack was racially motivated, KPIX reported.

“We haven’t connected him with any type of radical group or white supremacist group … but we are going to explore all options,” Chief Rojas said.

The attack, and Cowell’s subsequent flight, were captured on surveillance cameras inside the train station and in the parking lot, the chief said.

He said Powell began removing his clothing as he fled through the parking lot, which police interpreted to be a guilty action.

“We have recovered what we believe to be the murder weapon,” the chief told reporters. He said investigators found a knife at an adjacent construction site.

Friends and family planned a vigil in Nia Wilson’s memory on Monday night. Hundreds of supporters gathered in a group that filled the BART station and spilled out onto the street, KGO-TV reported.

Lahtifa Wilson attended the gathering honoring her sister with a bandage on her neck where she had been stabbed.

“She didn’t do nothing to nobody,” said Lahtifa Wilson. “I didn’t do nothing to nobody.”

The sisters were returning home from a family gathering together when the incident occurred on the BART platform.

“She’s just yelling my name, ‘Tifa, Tifa, Tifa’ and I said, ‘I got you baby, I got you,'” Lahtifa Wilson told KGO. “And I looked back and he was wiping off his knife and stood at the stairs and just looked.”

Cowell was captured on another BART train at about 6:30 p.m. on Monday, the San Francisco Gate reported.

Chief Rojas told reporters that police received the first tip about Cowell’s whereabouts at about 5:45 p.m., when a witness reported he’d gotten on a train at Coliseum Station bound for Richmond.

Then another rider contacted police and said they’d seen Cowell jumping onto an Antioch-bound train shortly thereafter, the chief said.

Police intercepted Cowell on a train at Pleasant Hill, where he was located and taken into custody after officers searched the train.

His arrest went without incident, and police said he wasn’t armed and provided his real identification when asked by officers, the chief said.

Chief Rojas described the incident as a “prison-type attack,” where he jumped his victims from behind and then quickly took off.

“It basically happened at the snap of the fingers, at the drop of the pin … that quick,” he said. “The officers were at the station, and as soon as they were notified, they reacted.”

The chief said the two officers in the station provided first aid to the Wilson sisters as they waited for an ambulance.

The vigil for Nia Wilson that began around 4 p.m. on Monday quickly grew into a protest, as about 1,000 citizens showed up chanting and waving signs.

The protesters started out at the BART station where Nia Wilson was fatally stabbed, but then marchers headed into downtown to confront an far group called the Proud Boys who were meeting at the Make Westing bar located at 18th and Telegraph, KPIX reported.

Violence broke out between the two groups at about 8 p.m., as helicopters hovered overhead.

When officers attempted to detain two people, the crowd began throwing M80s at the police, KPIX reported.

Oakland police deployed one chemical agent to help disperse the crowd, according to KPIX.