MANCHESTER, England (CNN) - A flurry of raids and arrests on Wednesday took aim at a terror network associated with the former university student who conducted the bombing at an Ariana Grande concert in Manchester days after returning from Libya, officials say.
Salman Abedi, a 22-year-old British-born national of Libyan descent, has been identified by police as the suicide bomber in the Manchester Arena attack Monday night.
The first images of the device Abedi is thought to have used to kill at least 22 people, including children, emerged Wednesday.
The New York Times posted photos that show what it said could be the detonator, a battery, nuts and screws for shrapnel, and fragments of a backpack used in the attack.
Meanwhile, two more victims were named, teenagers Chloe Rutherford and Liam Curry, who their families said were 'inseparable."
A sixth man was arrested late Wednesday in connection with the bombing. A woman arrested earlier in Blackley has been released without charge. The brother of the Manchester bomber was arrested in Libya. A friend of the attacker's family says Abedi went to Libya after getting into trouble in UK. Manchester United win the Europa League on emotional night two days after bombing
New details about Abedi emerged Wednesday -- including alleged links to terror groups, his troubles in Manchester after the death of a friend, his travel to Libya with a younger brother and their father's attempts to keep them from returning to the UK.
"It is very clear that this is a network we are investigating," Greater Manchester Police (GMP) Chief Constable Ian Hopkins said.
Six men have been arrested over the past two days in connection with the attack. They were taken into custody in the Manchester area and Nuneaton, about 100 miles southeast of Manchester, in the British Midlands.
A woman arrested during a raid on flats in Blackley has since been released without charge, according to the Greater Manchester Police.
Up to 3,800 military personnel have been made available to patrol key locations following the attack, Secretary Rudd said, and almost 1,000 are deployed.
As police worked to learn more about the extent of Abedi's network, more victims of the bombing were named.
Among the dead are 8-year-old Saffie Rose Roussos from Leyland, and 15-year-old Olivia Campbell. Cheshire Police said one victim was an off-duty female officer. She was not identified.
Tributes were also paid to teenagers Chloe Rutherford, 17, and Liam Curry, 19, who were described by their families as "beautiful inside and out."
On Thursday, the UK will hold a minute of silence two days after Prime Minister Theresa May said Britain's threat level was raised from "severe" to "critical," and warned a "further attack may be imminent."
Late Wednesday, Manchester United beat Ajax 2-0 to win the Europa League soccer tournament as fans in the stands in Stockholm, Sweden, carried banners saying, "Manchester stands against terrorism."
Bomber's brother arrested in Libya
Abedi was on the radar of intelligence services, Home Secretary Amber Rudd told the BBC.
The bomber was in Libya for three weeks and returned days before his attack, US military officials assigned to US Africa Command told CNN.
In Libya, Abedi's brother -- identified as 20-year-old Hashim Ramadan Abu Qassem al-Abedi -- was arrested Tuesday night on suspicion of links to ISIS, said a statement from a Tripoli militia known as the Special Deterrence Force.
The younger Abedi was allegedly planning a terror attack in Libya when arrested, the militia reported. He was picked up while allegedly receiving a money transfer from Salman Abedi.
CNN has not been able to independently verify the details from the militia. The UK Foreign Office, Metropolitan Police and Greater Manchester Police had no immediate comment on the reported arrest in Libya.
The militia claims the younger Abedi admitted knowledge about the Manchester attack and was in Britain for its planning. The statement also said he left the UK in mid-April and had been under surveillance about a month and a half.
Sons got in trouble?
Abedi's father brought Salman and his younger brother to Libya from Manchester about a month ago because they were getting in trouble in England, a family friend in Libya told CNN.
The father, a police officer whose name is Ramadan, took his sons' passports so they could not travel, the friend said.
The friend and another source in Manchester's Libyan community said Salman got his passport back after telling his father he was going on a pilgrimage to Saudi Arabia. He returned to England instead.
Abedi carried out the attack three days after returning to the UK, said the family friend, who described the father as "shaking" after learning of his son's involvement.
US military officials said American and UK intelligence services, along with the Africa Command, are looking at the possibility Abedi could have met with ISIS members or operatives from al Qaeda in the Islamic Maghreb, a North African militant organization.
Rudd earlier slammed the US for leaking several details on the attack investigation as "irritating" and asked them to stop.
Rudd refused to respond to Collomb's comments that Abedi was believed to have been to Syria. She also refused to elaborate on reports in Arab media Abedi's father had links to Islamist rebel groups in Libya.
Attacker's ties to Libya
Abedi's three weeks in Libya has raised questions about his travel and how aware British authorities were of him and his movements in recent weeks.
US Africa Command, which oversees US military involvement in Libya, is using contacts there to learn where Abedi went and whom he might have met with, US military officials said.
Abedi was a student at the University of Salford in Manchester. The university said he studied business and management but was not attending this semester.
Libya has become a hotspot for terrorism since the downfall and death of dictator Moammar Gadhafi in 2011. ISIS has gained a foothold in the country, and a tenuous UN-backed government there has struggled to assume full command of the security situation.
ISIS claimed Monday's attack, saying on its Telegram channel Tuesday that a "soldier of the caliphate" planted explosive devices at the arena, according to a US counterterrorism source. ISIS routinely claims attacks with which it has no proven connection.