An American woman was killed and another five were injured in a stabbing in central London late Wednesday night that authorities initially said may have been an act of terrorism, but said Thursday it was not, according to multiple reports.

Around 10:30 p.m. local time, a knife-yielding man attacked people in London's Russell Square. Police tasered the assailant and took him into custody.

"A man was arrested at 10:39 p.m. and a Taser was discharged by one of the arresting officers," a Scotland Yard official told the Daily Mail.

Mark Rowley, assistant commissioner in the Metropolitan police and Britain's most senior counter terrorism officer, said they are looking into the suspect's mental health background.

"Early indications suggest mental health is a significant factor in this case and that is one major line of inquiry," Rowley said in a press conference early Thursday morning. "But of course at this stage we should keep an open mind regarding motive and consequently terrorism as a motivation remains but one line of inquiry for us to explore."

The condition of the five wounded is still unknown.

This story will be updated.