Train hit by explosion can carry a total of 865 passengers
The explosion on the London Underground occurred on an S-Stock train which can carry more than 800 passengers.
The S-Stock were the first Tube trains to have walk-through carriages to boost capacity when they were introduced to the network in 2010.
Alarmed passengers would have theoretically been able to run from one end of the train to the other because of the lack of interconnecting doors.
S7 trains are used on the District, Circle and Hammersmith & City lines, and consist of seven carriages.
The trains have 356 seats and a total capacity of 865 passengers.
Witnesses described the train involved in the explosion as "absolutely packed".
The incident happened at around 8.20am, just after the busiest time of day at Parsons Green station, which is between 8am and 8.15am.
