Here is everything we know so far:
– The explosion happened inside a taxi outside the hospital moments before 11am on Remembrance Sunday.
– Emergency services were on the scene within minutes and one man, the passenger in the taxi, was pronounced dead.
– The driver of the taxi, named locally as David Perry, was injured but managed to escape and has since been released from hospital.
– He picked up the passenger in the Rutland Avenue area of Liverpool, roughly a 10-minute drive from Liverpool Women’s Hospital, said Assistant Chief Constable Russ Jackson, from Counter-Terrorism Policing North West.
– Detective Chief Inspector Andrew Meeks said on Monday: “Our inquiries are very much ongoing but at this stage we strongly believe that the deceased is 32-year-old Emad Al Swealmeen.”
– Officers said an explosion came from within the car as it approached the drop-off point.
– Police have declared the event a “terrorist incident” and said the proximity in location and time to Remembrance services was a “line of inquiry”, though officers cannot draw a connection “at this time”.
– The UK terror threat level was raised to severe in the wake of the incident, meaning an attack is highly likely.
– Officers say “inquiries indicate that an improvised explosive device has been manufactured” and are working under the assumption the passenger built it in the taxi.
– They believe they know the identity of the passenger but have not confirmed it publicly.
– The suspect is understood to be of Middle Eastern origin and reportedly settled in Britain several years ago.
– Official sources confirmed to the PA news agency that the man who died was not previously known to the security services.
– Detectives are unsure what the motivation behind the attack was, the reason for the device’s “sudden explosion” or why the passenger asked to be taken to the hospital.
– Three men aged 21, 26 and 29 were detained on Sunday in Sutcliffe Street in the nearby Kensington area of the city.
– A fourth man, aged 20, was arrested on Monday, also in the Kensington area.
– All were arrested under Section 41 of the Terrorism Act, under which officers can detain terror suspects without a warrant, and will be interviewed on Monday.
– Two addresses, one in Sutcliffe Street and another in Rutland Avenue, have been searched, with the second address yielding “significant items”, Mr Jackson said.
– DCI Meeks said on Monday: “We believe he (Emad Al Swealmeen) lived at the Sutcliffe Street address for some time and had recently rented the Rutland Avenue address.”
– Eight families were evacuated from near the Rutland Avenue address and a cordon is in place.
– Prime Minister Boris Johnson praised the taxi driver for acting with “incredible presence of mind and bravery”, while mayor of Liverpool Joanne Anderson lauded the driver for his “heroic efforts”.
– Liverpool Women’s Hospital said visiting access had been restricted “until further notice” and there was an increased security and police presence on the site.
– A controlled explosion was carried out in Sefton Park on Monday afternoon “as a precaution” as part of the investigation, police said.