Homemade bomb explodes on packed London subway

Police officers on the scene during a search on an address in Stanwell on Sept. 17, 2017 in London, England. A second man has today been arrested in connection with the Parsons Green attack which left 30 injured. (Photo: Jack Taylor/Getty Images)

Police and forensic officers work at a property in Sunbury-on-Thames, southwest London, as part of the investigation into Friday’s Parsons Green bombing, Saturday Sept, 16, 2017. British police made what they called a “significant” arrest Saturday in southern England following the partially exploded bomb attack on the London subway. (Photo: Victoria Jones/PA via AP)

Police officers work near a property in Sunbury-on-Thames, southwest London, as part of the investigation into Friday’s Parsons Green bombing, Saturday Sept, 16, 2017. (Photo: Victoria Jones/PA via AP)

A passenger walks onto the platform at Parsons Green subway station after it was reopened following a terrorist attack on a train at the station yesterday in London, Saturday, Sept. 16, 2017. (Photo: Tim Ireland/AP)

Police forensics officers works alongside an underground tube train at a platform at Parsons Green underground tube station in west London on September 15, 2017, following an incident on an underground tube carriage at the station. (Photo: Adrian Dennis/AFP/Getty Images)

People react near Parsons Green tube station in London, Britain, Sept. 15, 2017. (Photo: Hannah McKay/Reuters)

Emergency services attend to the scene near Parsons Green Underground Station on Sept. 15, 2017 in London, England. (Photo: Jack Taylor/Getty Images)

Personal belonglongs and a bucket with an item on fire inside it, are seen on the floor of an underground train carriage at Parsons Green station in West London, Britain, Sept. 15, 2017, in this image taken from social media. (Photo: Sylvain Pennec via Reuters)

Members of the emergency services work near Parsons Green underground tube station in west London on Sept. 15, 2017, following an incident on an underground tube carriage at the station. (Photo: Daniel Leal-Olivas/AFP/Getty Images)

An injured woman is led away after an incident at Parsons Green underground station in London, Britain, Sept. 15, 2017. (Photo: Luke MacGregor/Reuters)

Armed police officers walk through a carriage of a London underground tube train at Parsons Green station in London, Britain, Sept. 15, 2017. (Photo: Hannah McKay/Reuters)

A woman reacts outside Parsons Green tube station in London, Britain, Sept. 15, 2017. (Photo: Kevin Coombs/Reuters)

In this aerial image made from video, police officers work at the Parsons Green Underground Station after an explosion in London Friday, Sept. 15, 2017. (Photo: Pool via AP)

Police with dogs keep watch over FC Koln fans during the Europa League match against Arsenal at the Emirates Stadium, London, Thursday Sept. 14, 2017. (Photo: Nick Potts/PA via AP)

In this image made from video, a woman with blankets wrapped around her is being escorted by emergency services near the scene of an explosion in London Friday, Sept. 15, 2017. (Photo: Sky via AP)

Police and an ambulance stand near Parsons Green subway station in London, Friday, Sept. 15, 2017. (Photo: Frank Augstein/AP)

A police officer holds cordon tape near Parsons Green subway station in London, Friday, Sept. 15, 2017. (Photo: Frank Augstein/AP)

A woman walks with her child past police cordon near Parsons Green tube station in London, Britain, Sept. 15, 2017. (Photo: Hannah McKay/Reuters)

Police officers escort members of the public out of their inner cordon as they work near Parsons Green underground tube station in west London on Sept.15, 2017, following an incident on an underground tube carriage at the station. (Photo: Daniel Leal-Olivas/AFP/Getty Images)

A forensics officer on the platform at Parsons Green station in west London after Scotland Yard declared a terrorist incident following a blast which sent a “fireball” and a “wall of flame” through a packed London Underground train. Friday, Sept. 15, 2017. (Photo: Dominic Lipinski/PA via AP)

A police officer escorts an injured woman from the scene at Parsons Green Underground Station on September 15, 2017 in London, England. (Photo: Chris J Ratcliffe/Getty Images)

In this aerial image made from video, emergency workers help people to disembark a train near the Parsons Green Underground Station after an explosion in London Friday, Sept. 15, 2017. (Photo: Pool via AP)

Members of the emergency services work near Parsons Green underground tube station in west London on September 15, 2017, following an incident on an underground tube carriage at the station. (Photo: Daniel Leal-Olivas/AFP/Getty Images)

Forensic officers are seen at Parsons Green Underground Station on Sept.15, 2017 in London, England. (Photo: Jack Taylor/Getty Images)

Police officers walk on the road near Parsons Green tube station in London, Britain, Sept. 15, 2017. (Photo: Kevin Coombs/Reuters)

An injured woman reacts outside Parsons Green tube station in London, Britain, Sept. 15, 2017. (Photo: Kevin Coombs/Reuters)

Police, fire and ambulance crew attend to an incident at Parsons Green underground station in London, Britain, Sept. 15, 2017. (Photo: Luke MacGregor/Reuters)

Police, fire and ambulance crew attend to an incident at Parsons Green underground station in London, Britain, Sept. 15, 2017. (Photo: Luke MacGregor/Reuters)

Armed policemen stand by cordon near Parsons Green tube station in London, Britain, Sept. 15, 2017. (Photo: Hannah McKay/Reuters)

Deputy Chief Constable Adrian Hanstock of the British Transport Police makes a statement to the media after an incident at Parsons Green underground station in London, Britain, Sept. 15, 2017. (Photo: Luke MacGregor/Reuters)

A police forensic officer stands beside the train, at left, where an incident happened, that police say they are investigating as a terrorist attack, at Parsons Green subway station in London, Friday, Sept. 15, 2017. (Photo: Frank Augstein/AP)