A man carrying a sword in east London killed oneand left four other people injured, including police officers, during an attack Tuesday morning.

A 36-year-old suspect was Tasered and then arrested at the scene. Footage from a bystander showed a man wearing a yellow sweater walking on the roofs of low-rise homes in a residential area in Hainault, a northeast area of London. A police officer yelled, “Drop your sword,” before warning residents to “lock your doors.”

Police said they were called just before 7 a.m. with reports that a vehicle had driven into a house and that people were being stabbed.

Chris Bates, a local resident, told the BBC that the attacker “had a big samurai sword, basically. It was a huge sword. I saw it all from my bedroom window, and then when he went into the driveway, a couple doors down, I ran outside and then the police Tasered him there.”

The Metropolitan Police’s Chief Superintendent Stuart Bell told reporters at the scene that an investigation was “in its very early stages” but that the incident was not being treated as terror-related or reflective of a broader threat.