(CNN) — Five terrorists — three dead, two whose fates are unknown.
So far, that’s how many people that authorities say played a part in Tuesday’s terror attacks in Brussels, Belgium, that killed 31 people and injured 270.
Two were allegedly involved in bombing a train near the Maelbeek metro station. Of them, one has been identified as Khalid El Bakraoui, who died in that suicide attack. And on Thursday, a senior Belgian security source told CNN that authorities believe a second, unnamed person was also involved in that blast. That man’s whereabouts — and whether he’s dead or alive — is unknown.
Surveillance footage shows this man holding a large bag at the station, according to Belgian public broadcaster RTBF. It’s not clear if he was among the at least 20 killed in the blast, RTBF said.
Three more people apparently took part in the Brussels Airport attack. At least two of them are dead — Khalid’s brother Ibrahim El Bakraoui and ISIS bomb maker Najim Laachraoui. Authorities also have a grainy image of another suspect who they believe is on the run.
And they’ve uncovered what appears to be a hideout in a Brussels suburb, where they found 15 kilograms (33 pounds) of the explosive TATP, screws and other bomb-making materials, Belgian federal prosecutor Frederic Van Leeuw said.
But they won’t be getting any information from Salah Abdeslam, the suspect in November’s Paris terror attacks who used a Brussels apartment rented by Khalid Bakraoui as a hideout before his capture last week, according to a Belgian security source.
He is no longer cooperating with police, his lawyer said Thursday. Abdeslam wants out of Belgium and to be extradited to France as soon as possible.
Any clue, any lead, any witness could be critical in the race to stop the next terrorist attack on European soil.
CNN intelligence and security analyst Bob Baer thinks people have reason to worry, given all the munitions authorities have found so far — and, more so, those they still haven’t discovered. He says Britain or France could be hit next.
“I think they’re shocked by the amount of armament and the number of followers and how big the network was connected to Paris and now Brussels,” Baer said.
As CNN International Diplomatic Editor Nic Robertson puts it: “The dam has broken.”
Unraveling that network may take some time, however.
Baer says that European authorities are late to the game when it comes to developing a network of sources inside the communities where terrorists thrive.
“These communities of North African origin are very tight-knit,” he said. “It’s very difficult for the European services to get inside of them. They were ignored for so many years.”
Abdeslam — despite being Europe’s most wanted man for four months as the lone surviving Paris attacker — managed to hide in plain sight just blocks from the Brussels neighborhood where he grew up.
The fact that no one gave him up is troubling. What may be more worrisome is if there are more young men like him, who sympathize not with Europeans but with ISIS, the terror group that’s taken over swaths of territory in Syria and Iraq while claiming attacks elsewhere around the world, including in Brussels and Paris.
“Today, Belgium has been trying to hold back another force of nature: A disaffected, disassociated youth, warped and wrapped in ISIS’s corrosive ideology,” CNN’s Robertson said. “Their numbers have been too great for Belgian counterterrorism efforts to cope.”
Turkey caught one of the bomber brothers
Authorities are going after the remaining subway bombing suspect. They’re also looking for another man, shown in surveillance images with a hat and light-colored clothing, who’s suspected of dropping off a bomb at the Brussels Airport then leaving. As they work to prevent more bloodshed, there’s also a focus on whether those responsible for Tuesday’s carnage could have been stopped.
Turkey deported Ibrahim El Bakraoui to the Netherlands last year, a senior Turkish official told CNN. The Turkish presidency’s office said authorities there captured him in July 2015 and flagged him to Belgian authorities.
Belgian authorities, the Turkish official said, responded soon after, saying he had a criminal record but no known ties to terrorism.
“These two deceased suicide bombers had lengthy criminal records,” Van Leeuw, the Belgian prosecutor, said Wednesday, “but (were) not linked to terrorism.”
In October 2010, a Brussels criminal court sentenced Ibrahim El Bakraoui to nine years behind bars for opening fire on police officers with a Kalashnikov during a robbery, according to broadcaster RTBF and CNN affiliate RTL.
Interpol had issued a “red notice” for Khalid El Bakraoui, the subway bomber, that noted that Belgian authorities wanted him in connection with terrorism. But it wasn’t clear when that notice was issued or why Belgian authorities now say he had no ties to terrorism.
Laachraoui himself had been named as a suspect in the Paris attacks. Abdeslam could be another link, with Belgian officials saying he may have been helping plan new attacks at the time of his capture.
Investigators suspect Abdeslam planned to be part of an attack by the same ISIS cell that lashed out Tuesday in Brussels, a senior Belgian counterterrorism official told CNN’s Paul Cruickshank.
Raids, arrests, a will
Two people were arrested in Brussels on Tuesday in connection with the attacks — one in the northeast Brussels area of Schaerbeek and the other in Haren, Van Leeuw said. One was released later that day, he said. Another person was detained Wednesday, RTBF reported.
One raid, officials said, came after a tip from a taxi driver led them to Schaerbeek.
The driver recognized the men shown in surveillance footage and told authorities he’d driven them to the airport before the attacks. Police raided the area where the driver told them he’d picked up the men.
Investigators found bomb-making material, chemical products and an ISIS flag during a house search in Schaerbeek, according to Belgium’s prosecutor’s office.
They made another significant find nearby: Ibrahim El Bakraoui’s will, found on a computer in a trash can. The will indicated that he “needs to rush” and “no longer feels safe.”