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.

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."

Another piece of shrapnel that appears to be a bolt, seen on the floor near the area of the attack that killed 22 people.

Another piece of shrapnel that appears to be a bolt, seen on the floor near the area of the attack that killed 22 people.

A screw on the floor of the foyer of the Manchester Arena that may have been packed into the device.

A screw on the floor of the foyer of the Manchester Arena that may have been packed into the device.

This is what's left of a battery that could have been used to power the device.

This is what's left of a battery that could have been used to power the device.

Shrapnel from the Manchester terror attack at the Ariana Grande concert.

Shrapnel from the Manchester terror attack at the Ariana Grande concert.

A ruler shows the length of a possible detonator that was reported to have been found in the suspect's left hand.

A ruler shows the length of a possible detonator that was reported to have been found in the suspect's left hand.

Another, closer image of the bag said to have been carried by the suspect, Salman Abedi, a 22-year-old British-born national of Libyan descent.

Another, closer image of the bag said to have been carried by the suspect, Salman Abedi, a 22-year-old British-born national of Libyan descent.

Images first posted by The New York Times show what remains of a backpack reportedly used to carry the bomb used in a suspected suicide attack at the Ariana Grande concert in Manchester on Monday, May 22.

Key developments

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

Suspects arrested

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.

The victims

As police worked to learn more about the extent of Abedi's network, more victims of the bombing were named.

Tribute from the family of Chloe Rutherford, 17, and the family of Liam Curry, 19 pic.twitter.com/nVNf8dS0ZQ — G M Police (@gmpolice) May 24, 2017

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.

Hashim Ramadan Abu Qassem al-Abedi, a brother of Manchester bomber Salman Abedi was arrested in Tripoli, Libya, May 23.

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.

Soldiers on patrol at the Prime Minister's office in London on Wednesday.

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.

Photos: Deadly explosion at Ariana Grande concert People in Manchester, England, gather in St. Ann's Square on Thursday, May 25. They were observing a national minute of silence to remember the victims of a suicide bombing at an Ariana Grande concert. Hide Caption 1 of 22 Photos: Deadly explosion at Ariana Grande concert Britain's Queen Elizabeth II speaks to 15-year-old Millie Robson and her mother, Marie, during a visit to the Royal Manchester Children's Hospital on May 25. The Queen was visiting those injured in the attack. Hide Caption 2 of 22 Photos: Deadly explosion at Ariana Grande concert A police officer guards a house in Manchester as investigations continued on May 25. Police say a man carrying explosives acted as a lone attacker and died in the blast. Hide Caption 3 of 22 Photos: Deadly explosion at Ariana Grande concert Flowers and tribute messages are left for victims in St. Ann's Square. Hide Caption 4 of 22 Photos: Deadly explosion at Ariana Grande concert A women sheds tears after observing the minute of silence in St. Ann's Square. Hide Caption 5 of 22 Photos: Deadly explosion at Ariana Grande concert A Manchester road is closed off as police raids continued on May 25. Hide Caption 6 of 22 Photos: Deadly explosion at Ariana Grande concert Local residents hold Manchester City and Manchester United soccer jerseys during the national minute of silence. Hide Caption 7 of 22 Photos: Deadly explosion at Ariana Grande concert Police officers deliver flowers to a makeshift memorial in Manchester on Wednesday, May 24. Hide Caption 8 of 22 Photos: Deadly explosion at Ariana Grande concert Women cry after placing flowers in Manchester on May 24. Hide Caption 9 of 22 Photos: Deadly explosion at Ariana Grande concert A forensics team works at the scene of the explosion on Tuesday, May 23. Hide Caption 10 of 22 Photos: Deadly explosion at Ariana Grande concert British Prime Minister Theresa May condemns the "callous terrorist attack" as she delivers a statement in London on May 23. Hide Caption 11 of 22 Photos: Deadly explosion at Ariana Grande concert Police help someone after the attack at Manchester Arena on Monday, May 22. Hide Caption 12 of 22 Photos: Deadly explosion at Ariana Grande concert People gather outside the arena. "We can confirm there was an incident as people were leaving the Ariana Grande show last night," police said on Twitter early on Tuesday. "The incident took place outside the venue in a public space. Our thoughts and prayers go out to the victims." Hide Caption 13 of 22 Photos: Deadly explosion at Ariana Grande concert People receive medical attention at a railway station close to the arena. The incident happened shortly after Grande had left the stage, shortly after 10:30 p.m. (5:30 p.m. ET) according to eyewitnesses. Calvin Welsford, an 18-year-old concertgoer, said that he heard a "loud bang" a couple of minutes after Grande's set had finished. Hide Caption 14 of 22 Photos: Deadly explosion at Ariana Grande concert Paramedics respond to the scene. Hide Caption 15 of 22 Photos: Deadly explosion at Ariana Grande concert Emergency workers and concert attendees gather outside the arena. Hide Caption 16 of 22 Photos: Deadly explosion at Ariana Grande concert People stand by a cordoned-off street close to the arena. Hide Caption 17 of 22 Photos: Deadly explosion at Ariana Grande concert Greater Manchester Police tweeted that emergency services were "responding to (a) serious incident at Manchester Arena. Avoid the area. More details will follow as soon as available." Hide Caption 18 of 22 Photos: Deadly explosion at Ariana Grande concert People are escorted away from the arena. Hide Caption 19 of 22 Photos: Deadly explosion at Ariana Grande concert People sit outside near the arena. The crowd was made up of mainly younger people who had come to see Grande in her first of three scheduled concerts in the UK. Hide Caption 20 of 22 Photos: Deadly explosion at Ariana Grande concert An injured man is helped at the scene. Hide Caption 21 of 22 Photos: Deadly explosion at Ariana Grande concert People hug near armed police who responded to the scene. Hide Caption 22 of 22

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.

Police safeguard Buckingham Palace in London on Wednesday.

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.