Police could be seen investigating the scene where a woman was killed and five other people injured by a man with suspected mental health issues who went on a rampage with a knife in central London.
Police say the attack in Russell Square could be linked to terrorism.
Armed police were called at 10:33 p.m. (2133 GMT) after a man with a knife started to attack people.
A 19-year-old man has been arrested on suspicion of murder.
"Saw the body. We've seen all these cops lined up down the street with machine guns held in their hands. As you can see, they've blocked off the whole street so they had that all blocked off last night as well and that's all we've really seen. We got interviewed by the cops and they told us if we had witnessed anything and we said 'not really'", an Australian tourist Gary Griffiths said.
A woman who was in the area just after the attack said she thought there had been a motorcycle accident.
"I came out of the hotel for a cigarette from the bar and I just stood there and I saw people just looking on the ground and someone laying down, or a couple of people laying down and then a guy with a motorbike helmet balanced on his head was going up and down the street and then the police and the ambulance came and I went back into the hotel," she said.
The victim was treated at the scene but pronounced dead a short time later. The other injured - one woman and four men - were treated in hospital. Three were later discharged.