During the morning rush hour, an improvised explosive device detonated on a District Line train at Parsons Green station in southwest London, producing a significant fireball and injuring over 30 people. Eyewitnesses described a sudden explosion that caused considerable panic, with passengers attempting to flee the train in a mass evacuation. The device was a homemade bomb placed in a supermarket shopping bag, which partially failed to fully detonate. This incident occurred within a backdrop of heightened concerns regarding terrorism in the United Kingdom, particularly following previous attacks in London earlier that year.

Emergency services reacted quickly, establishing a large cordon around the station and conducting thorough searches of the area. The event prompted a swift response from the Metropolitan Police and local authorities, who declared it a terrorist incident. Following the attack, Prime Minister Theresa May convened an emergency meeting of the Cobra committee to monitor the situation and coordinate responses. The attack was later claimed by Islamic State, indicating a broader trend of terrorist activities aimed at public transport networks in Europe.

The investigation into the incident revealed crucial details about the suspect, who was identified as an 18-year-old Afghan asylum seeker, later arrested in connection with the bombing. Authorities delved deeper into their methods and networks, intensifying counter-terrorism efforts across London and the UK. This incident heightened public awareness of the potential for attacks on public services, leading to ongoing discussions about security and counter-terrorism measures.