Ten things you need to know about the Parsons Green bomb attack

An explosion involving an improvised explosive device at Parsons Green Tube station has left 29 people injured. This is what we know so far about the attack.

:: Emergency services were called to the west London station at around 8.20am following reports of an explosion.

:: The District Line train bound for central London had just stopped at the station when the blast happened, reportedly in the last carriage of the train.

:: Witnesses said they saw a white "builder's bucket" in a supermarket bag, with pictures on social media showing a flaming bucket with wires protruding inside a plastic bag on the floor of the carriage.

:: People reported seeing a "fireball" and a "wall of flame" and the injured "covered in blood".

:: Those caught up in the blast reported "panic" as people fled the station, with some saying there was a crush as commuters, including children, tried to get out.

:: The Metropolitan Police have confirmed they are treating the blast as a terrorist incident and a manhunt is under way.

:: Theresa May has condemned the "cowardly" attack, saying it involved a device "clearly intended to cause significant harm".

:: Sky sources say police have identified a suspect from CCTV footage and that the device, which had a timer, did not fully detonate.

:: Most of the 29 people injured suffered "flash burns" and none of them are thought to be in a life threatening or serious condition.

:: The UK's terror threat level will remain at severe, meaning an attack is highly likely, and will be kept under review as the investigation continues.