On 7 July 2005, four suicide bombers struck in central London.
Three bombs went off there - three on London underground stations and one on a bus.
The underground station bombs went off at about 8.50am just outside Liverpool Street and Edgware Road stations, and one tube train travelling between King's Cross and Russell Square.
A fourth bomb went off on a bus in Tavistock Square, London, about an hour later.
The attacks became known as the 7/7 bombings.
Sadly, 52 people died in the attacks and more than 770 people were injured.