Britain Monday raised its terror threat level from substantial to severe following an explosion Sunday in a taxi outside a hospital in the city of Liverpool, Interior Minister Priti Patel announced.
A severe level means a terror attack is "highly likely."
Prime Minister Boris Johnson also chaired an emergency meeting in response to the incident.
Authorities told reporters that the passenger in the taxi was carrying an improvised explosive device and asked to be taken to the Liverpool Women’s Hospital, but that a motive or what caused the device to explode was not clear.
The passenger died in the blast, and police said Monday they believe they know his identity.
Since the explosion, police have arrested four other men in connection with the investigation.
The explosion injured the taxi driver, who received medical treatment but has been released.
Some information for this report came from the Associated Press and Reuters
