A California man has been arrested for stabbing two sisters in the neck on a train platform in Oakland, ending a day-long manhunt. One of the victims, Nia Wilson, died as a result of her injuries.

John Lee Cowell was arrested by Bay Area Rapid Transit police on Monday night after he allegedly stabbed 18-year-old Wilson and her sister Letifah Wilson, 26, on the platform of the MacArthur station in Oakland, California Sunday, according to a statement by BART police.

Both sisters were stabbed in the neck. Nia died at the scene and Letifah sustained serious injuries and was treated by a local hospital. Cowell has been charged with first degree murder, jail records show.

Police were at the station after receiving a report of a man with a knife. Once they arrived on the platform, however, Cowell had left the scene and the two women had already been stabbed. Investigators reviewed surveillance tape from the train and the station and were able to identify Cowell, 27, as the suspect.

Cowell was apprehended a day later after police received a tip from an anonymous BART rider who had spotted the him on a train. Police took him into custody without incident on board a BART train, according to police.

The violent attack brought widespread condemnation from the public and officials, and the BART Police Chief Carlos Rojas described the attack as one of the most vicious assaults he has seen in 30 years of policing. On social media, people speculated that Cowell’s attack was racially motivated. Cowell was white and the two victims were black.

Rojas was not able to confirm if the attack was based on racial hostility, but is considering all options in the investigation.

After speaking with the district attorney, Oakland City Council member Lynette McElhaney said in a statement that the DA was still considering if Cowell will be charged with a hate crime.

Cowell had been released from prison in May following a two-year sentence for second-degree robbery and was on parole at the time of the crime.