On Friday, several blasts and gunfire rang out in the Schaerbeek district of the Belgian capital, where police had earlier discovered bomb-making material during a major raid.

The explosives were found in an apartment that had reportedly been used by the suicide attackers who killed 31 people in attacks at Brussels Airport and in the subway on Tuesday. Local mayor Bernard Clerfayt said they were controlled explosions. Brussels airport officials said on Saturday that flights will not resume before Tuesday as damage is assessed following the twin bomb blasts.

A bomb disposal robot was sent to a light rail stop in Schaerbeek

Police also sealed off an area at a light-rail stop, where explosives experts were seen at the platform working with a bomb disposal robot. A man sitting with a young girl and holding a bag at the tram stop was reportedly ordered by police "to put the bag far from him."

According to local eyewitnesses, police then shot him twice in the leg and sent the robot to search the bag. The girl was reportedly taken into safe custody.

An eyewitness told Reuters that the police came, took the little girl who was shouting "Dad," adding that "she seemed terrified and the man got shot in the leg anyway because he was still moving."

Authorities also confirmed that one of the two attackers at the Brussels Zaventem airport also produced the explosive vests used in last year's assaults in Paris on November 13, establishing the most definitive link yet between the two attacks.

Forensic analysis confirmed that 24-year-old Najim Laachraoui's DNA was found on a suicide vest in Brussels and on a bomb used in the Paris attacks.

Authorities said they believe that both the Brussels attacks and the bombings in Paris were plotted from Belgium. Both attacks have been claimed by the self-styled "Islamic State" (IS) group.

Abdeslam keeping his silence

The top suspect in the Paris bombings, Salah Abdeslam, captured in Brussels one week ago, just days before the attacks, has insisted on exercising his right to silence, prosecutors said Friday.

Abdeslam has stopped cooperating with police and "no longer wants to talk," Belgian Justice Minister Koen Geens said.

France is currently seeking Abdeslam's extradition for trial, which his lawyer said Abdeslam is prepared to accept.

Kerry to IS: 'We will eliminate your nihilistic beliefs'

In a visit to Brussels on Friday, US Secretary of State John Kerry laid a wreath at the airport for the victims of the bombings. Belgian Prime Minister Charles Michel had to cancel his attendance because of the continuing police operations.

Kerry defended Belgium's ongoing counterterrorism efforts, despite the surfacing of a series of security and intelligence failures that have raised sharp criticism of the government. The secretary of state said that the "carping" about Belgium's shortcomings was "a little bit frantic and inappropriate," while reaffirming the US' support in the fight against terrorism.

US Secretary of State John Kerry said the US would not "rest" until it annihilated the "Islamic State" and its beliefs

"We will come back with greater resolve - with greater strength - and we will not rest until we have eliminated your nihilistic beliefs and cowardice from the face of the Earth," Kerry said at the ceremony, addressing IS.

Meanwhile it was also revealed that one of the Brussels airport suicide bombers had been on a US counterterrorism watch list. According to Reuters news agency, Brahim El Bakraoui had been known to US authorities before the November attacks in Paris; his brother Khalid, who carried out a suicide bombing at Brussels' Maelbeek Metro station shortly after the airport bombing, had been put on the list shortly the Paris attack.

Investigations yielding results

In total, nine people have been arrested in Belgium and two in Germany since Tuesday's attacks. Newsmagazine "Der Spiegel" reported that one of the detainees in Germany had received a phone message with the name of the metro station bomber three minutes before the metro blast, along with the word "fin" - French for "end."

As the identities of the victims began to come to light, officials announced that US, UK, German, Chinese, Italian, French and Dutch citizens were among the dead. However, some still remain hopeful that their loved ones will be found alive four days after the attacks.

The attacks in Brussels, home to the European Union and NATO, have heightened security concerns around the world and raised questions about the ability of EU states to respond to the threat posed by militants.