Manchester police searched a property on Wednesday in their investigation into last week's suicide bombing as a clearer picture began to emerge about the attacker's actions in the four days preceding the assault.
Twenty-two people were killed and 116 were injured in the attack, which occurred at the end of an Ariana Grande concert in Manchester. The attack, carried out by 22-year-old Salman Abedi, was the deadliest in Britain in more than a decade.
On Wednesday, police were searching a property on Banff Road, about four miles south of Manchester Arena, the site of the blast. They set up a cordon and asked the public to avoid the area.
Police said Abedi is likely to have bought most of the bomb components himself and largely acted alone.
"Our enquiries show Abedi himself made most of the purchases of the core components, and what is becoming apparent is that many of his movements and actions have been carried out alone during the four days from him landing in the country and committing this awful attack," Russ Jackson, head of the Greater Manchester Police's northwest counterterrorism unit, said in a statement issued Tuesday evening.
But police also said they could not rule out the possibility that he may have been part of a wider network.
"It is vital that we make sure that he is not part of a wider network, and we cannot rule this out yet. There remain a number of things that concern us about his behaviour prior to the attack and those of his associates which we need to get to the bottom of," Jackson said.
Police have been attempting to retrace Abedi's movements ahead of the attack by examining CCTV footage and reviewing his phone calls.
Abedi, born in Britain to Libyan parents, reportedly had returned to Britain after a trip to Libya four days before the attack.
Police said they were "especially keen" to figure out why Abedi repeatedly returned to the Wilmslow Road area of Manchester. They also released an image of Abedi wheeling a blue suitcase and appealed to the public for more information about the suitcase.
Over the weekend, Britain's state of alert was downgraded from "critical" - the highest level - to "severe," and armed soldiers were gradually being withdrawn from high-profile sites, including Downing Street and Buckingham Palace.
Grande has announced that she will return to Manchester on Sunday for a benefit concert. Fans who were at her May 22 concert will be offered free tickets to the benefit concert, which will be televised and will include performances by Justin Bieber, Katy Perry, Coldplay and Miley Cyrus.