As Manchester was still reeling from the suicide bombing that left 22 people dead and dozens more injured, U.K. authorities and mobilized troops were busting down doors and searching for any accomplices on Wednesday.
Salman Abedi, 22, is suspected of committing the attack with a homemade explosive outside Manchester Arena, where American singer Ariana Grande had been performing. Shortly afterward, the Islamic State militant group took responsibility for the attack and Prime Minister Theresa May promised swift vengeance on any co-conspirators.
Many questions remained Wednesday afternoon, but the clues so far painted a picture of Abedi as a potentially radicalized "mule" who made frequent trips to North Africa and the Middle East as part of a network of terror.
Here's what we know:
Police Have Arrested Abedi's Father, Two Brothers
Authorities announced the arrest of five men on Wednesday in connection with the bombing, bringing the total arrests to six, including two of Abedi's brothers and his father.
Three of the men were collared in the U.K. They weren't identified and the charges weren't announced. They were taken in after the Greater Manchester police department executed warrants in South Manchester, where Abedi, a British citizen of Libyan descent, is thought to have lived. The Associated Press reports that one of the arrests ― a family man in his 40s, according to neighbors ― was made just blocks away from Abedi's home.
A fourth person, Abedi's younger brother Hashem, was arrested in Tripoli, Libya, over his suspected ties to ISIS, according to Reuters. Libyan counterterrorism authorities told The Washington Post that Hashem is suspected of "planning to stage an attack in Tripoli."
Their father, Ramadan Abedi, was also arrested Wednesday in Tripoli after telling AP that his other son Ismail had been taken in by police Tuesday morning.
May has raised the U.K.'s terror level to its highest point, "critical," and deployed military personnel to back up police across the nation.
"The investigation into the terrorist attack in Manchester is large-scale, fast-moving and making good progress," Mark Rowley, head of the National Counter Terrorism Policing unit, told NPR.
Abedi Likely Didn't Work Alone, Traveled To Middle East & North Africa
U.K. Interior Minister Amber Rudd said Salman Abedi likely didn't act alone. Investigators were looking into his travel to Syria and Libya as well as his alleged relationship with Raphael Hostey, a British recruiter for the Islamic State who was killed last year in a drone strike, according to The New York Times.
"I think it's very clear that this is a network that we are investigating," Manchester Chief Constable Ian Hopkins said Wednesday. "There's extensive investigations going on and activity taking place across Greater Manchester as we speak."
Abedi had returned to the U.K. from a three-week trip to Libya just days before the attack, according to U.S. military officials.
He had "proven" ties to the Islamic State, according to French Interior Minister Gérard Collomb, who did not offer details. Abedi had also traveled to Syria, an ISIS stronghold, Collomb said.
"[Abedi] traveled to Libya and then most likely to Syria, became radicalized and decided to commit this attack," Collomb told BFMTV.
His Father Said He's Innocent, But Friends Were Worried
A person claiming to be Abedi's former schoolmate recalled seeing a change in his behavior after an earlier trip overseas. "He was an outgoing, fun guy, but since he went to Libya in 2011 he came back a different guy," the source told Manchester Evening News. "He used to drink [and] smoke weed. Then all of a sudden he turned religious and I've not seen him since 2012."
Eventually, Abedi dropped out of school, according to The New York Times. One neighbor described him to the Times as "angry" and said "he scared some people."
Another neighbor reportedly said "a black flag with Arabic writing on it" flew over his roof a few years ago.
Ramadan Abedi, meanwhile, had maintained his son's innocence. "We don't believe in killing innocents. This is not us," he'd told AP, speaking from Tripoli before his own arrest.
Salman Abedi had been planning to travel from Saudi Arabia to Libya to spend the upcoming month of Ramadan with family, his father said, adding that they had spoken only five days ago and his son sounded "normal."
But an anonymous friend in Manchester told The New York Times that Abedi's parents had actually become concerned about his radicalization. At one point, they had seized his British passport, but later returned it so he could fly to Saudi Arabia. Instead, he returned to the U.K.