A man who triggered a suitcase bomb in a failed attack at a busy Brussels train station was a 36-year-old Moroccan citizen who was known to the police but was not wanted for terrorism-related offenses, the Belgian authorities said on Wednesday.
The man entered the Brussels Central Station at 8:39 p.m. on Tuesday, went downstairs from the main ticket hall and began shouting near a group of passengers, according to Eric Van der Sijpt, a spokesman for the federal prosecutor’s office.
He was carrying a suitcase bomb that contained nails and gas bottles, Mr. Van der Sijpt said. The man set off a partial and relatively harmless explosion.
He then left the bag behind while he went in pursuit of a station master, Mr. Van der Sijpt said, and it “exploded a second time, more violently.”
After the second explosion, the man went back upstairs, approached a soldier and screamed “Allahu akbar” (Arabic for “God is great”). The soldier opened fire, killing him. Initial reports that the man might have been wearing a suicide belt proved to be unfounded.
While the attack was successfully averted — and Belgian authorities praised the soldier for his quick response — it once again shone an uncomfortable spotlight on Belgium, a linguistically divided and politically fragmented country that has been used as a base by jihadists, many of whom have become radicalized there.
Militants based in Brussels were linked to deadly attacks in and around Paris in November 2015, and bombings of an airport and subway station in Brussels in March 2016. More than 160 people died in those sets of attacks, for which the Islamic State claimed responsibility.
A number of militants involved in the earlier attacks had roots in Morocco, including Abdelhamid Abaaoud, a ringleader of the Paris attacks who grew up in Belgium; Salah Abdeslam, one of the Paris attackers; Mohamed Abrini, who accompanied two suicide bombers in the Brussels airport attack; and Najim Laachraoui, a bomb maker who blew himself up at the Brussels airport. (Mr. Abdeslam and Mr. Abrini are being held awaiting trial.)
About 100,000 people with Moroccan citizenship live in Belgium,which has a population of 1.1 million. Moroccan-Belgians are the country’s largest minority group with roots outside the European Union.
Belgium, a home to the headquarters of the European Union and the North Atlantic Treaty Organization, has been on alert for more than 18 months.
Prosecutors said the suspect — whom they named only as Oussama Z. — came from Molenbeek, a working-class immigrant neighborhood that has been connected to Paris and Brussels attackers. He was known to police for sexual misconduct but not for terrorism.
The area has become synonymous with the perceived failure of Belgian authorities to tame Islamic militancy.
One Italian newspaper, fairly or not, has called Belgium “Belgistan” while President Donald J. Trump attracted the opprobrium of many Belgian citizens last year after he called Brussels a “hellhole” and argued that the country had been blighted by the failure of Muslims to integrate there.
The failed attack occurred on the eve of a summit meeting in Brussels at which leaders from across Europe, including Chancellor Angela Merkel of Germany and President Emmanuel Macron of France, were scheduled to discuss defense and security issues, among other topics.
Jan Jambon, the Belgian interior minister, said in an interview with VRT News on Wednesday that several homes had been raided overnight, and prosecutor’s said that included the suspect’s home in Molenbeek.
It was not clear whether the attacker had links to the Islamic State or to any other militant groups, but Mr. Jambon said investigators would be examining how the man was radicalized and that the authorities would continue looking to plug any gaps in Belgium’s security system.
“The modus operandi of I.S. keeps changing,” he said. “It’s a game of the poacher and the forest ranger — whenever the forest ranger approaches, the poacher goes elsewhere and finds new ways.”
While he added that it was essential to be vigilant in the face of security threats, he warned against an overreaction. “If you protect yourself everywhere against anything, in the end we will end up in a police state,” he said.
Following a national security council meeting, Prime Minister Charles Michel said there was no indication that another attack was imminent, adding that security would be intensified.
“We will not let ourselves be intimidated by terrorists,” he said. “Just recently we saw with the attacks in Great Britain that our absolute basic values, our freedom and democracy, are threatened. We need to remain vigilant for that, we need to continue our lives as normally as possible.”
Brussels Central Station was temporarily closed, but it had reopened by Wednesday morning, at which point trains and subways were running on time.
The nearby Grand Place, an imposing square and tourist destination, was partly evacuated after the attack. It too has fully reopened.