cnn's nina dos santos is tracking this from london. what are you hearing at this hour? >> reporter: well, things are looking calm outside of the london bridge station but it was a different picture about seb hours ago. when the specter of another deadly terror attack made its presence felt on the capital streets. [ sirens ] >> reporter: terror once again in the heart of london. passengers on this bus became witness to a shocking scene. >> it looked like members of the public were fighting with a man. it looked like he was trying to be pinned down on the pavement. it looked like a shine of light from the man on the floor and we realized it was a knife and then the police ran over with guns and it ended with the man being shot. >> reporter: police say they were called to the area just before 2:00 p.m. following reports of a stabbing. after being apprehended by ordinary londoners, a suspect wearing a hoax explosive device was shot dead by officers.