On July 23, 2005, four bombs were detonated on Londons public transportation system during the morning rush hour, killing 52 people and injuring more than 700. The bombings were carried out by four suicide bombers linked to Islamic extremist groups. The attacks were part of a larger wave of terrorism in the UK and Europe, marking a significant escalation in the threat from homegrown radicalism. The event led to heightened security measures across the city and the UK. The bombings are remembered as one of the deadliest terrorist attacks in London.