Story highlights

As nervous residents go about their day, police continue to execute raids, other operations

Belgian Prime Minister says his country needs to "improve" in its fight against terrorism

Some metro trains are passing through -- but not stopping -- at station where one bombing took place

Brussels, Belgium CNN —  

Explosions and gunfire Friday exacerbated the uneasy mood of Belgium’s capital, a city that has become the focal point in Europe’s fight against terrorism following the bloody attacks here just days ago.

Residents of Brussels anxiously moved on with their lives as more police raids followed the vicious attacks in which more than 30 people were killed Tuesday.

Police operations seem commonplace now, with several taking place Friday. One was in the district of Schaerbeek, near where a taxi driver picked up three conspirators and took them to Brussels Airport before the bombings.

Witnesses told CNN that during the police activity Friday they heard two explosions, while others reported gunfire near a subway station.

The effects are felt in neighborhoods swarmed by police, and near the sites of attacks. Brussels Airport won’t recommence passenger flights until Tuesday, at the earliest.

The operation ended with the arrest of one person linked to Tuesday’s attacks, Schaerbeek Mayor Bernard Clerfayt told public broadcaster RTBF.

The mayor said that arrested person was wounded. It was not clear if that individual was the same one the shopkeeper saw shot in the leg.

It’s hard to escape the tension in Brussels where soldiers line the streets near the central subway station, their hands gripping guns.

More metro stations are open – about half of the nearly 80 stops – but they still close at 7 p.m. instead of the usual 1 a.m. Some trains are running through the Maelbeek station, though it is closed. Workers overnight Thursday installed screens and plastic to cover up the bomb damage from the view of passing trains.

A Belgian man said the whole atmosphere in the city has “the feeling of war.” That may be true, but others welcome the added security.

“It makes me safe,” one woman said. “A lot safer.”

At the Maelbeek train station a white, large wreath had been left by the Pompes Funebres Islamiques (Islamic Funeral company). The man who left the flowers said they were leaving others at other sites in Brussels. And even though he declined an interview, he told CNN, “the terrorists were not real Muslims.”

Children also left notes among the flowers at Maelbeek with messages:

“Let’s stay united against this fear.”

“Let’s show them we are not afraid.”

“I am Muslim. Peace please.”

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Belgian authorities conducted searches in Schaerbeek for several hours into Friday morning, sealing off streets for several blocks. At one point, masked teams in hazmat gear could be seen exiting a building and heading toward a police van.

Friday’s raid came just days after police – acting on the taxi driver’s tip – raided an apartment in the district and uncovered 15 kilograms of the explosive TATP, chemicals, a suitcase with nails and screws, an ISIS flag and other equipment meant to make explosives, Belgian federal prosecutor Frederic Van Leeuw said.

These kinds of police actions suggest authorities’ urgency to catch those responsible for Tuesday’s massacres – and to prevent the next attack.

At least nine people have been arrested in the past day in Europe. Six people were taken into custody overnight in Belgium. Of those, three have since been released.

Meanwhile a man in France suspected of being in an “advance stage” of planning his own attack was also detained. Afterward, law enforcement found 2 kilograms (4.4 pounds) of TATP and a Kalashnikov rifle in a raid in Argenteuil on Paris’ outskirts, a source briefed on the investigation said.

Investigators know of additional plots in Europe, in various stages of planning, linked to the same networks that were behind the November Paris attacks and the latest ones in Brussels, according to U.S. counterterrorism officials. Those terrorists are tied to ISIS, the Islamist extremist group that has taken over swaths of Syria and Iraq while also staging attacks elsewhere around the world.

There’s also a growing feeling that those opposing ISIS can do more. Some of this relates to continuing military efforts in the Middle East. Some has to do with better intelligence and cooperation among allies.

Belgium, especially, has come under fire. Interior Minister Jan Jambon offered to resign after acknowledging missed opportunities to stop one of the suicide bombers, Ibrahim El Bakraoui. And Prime Minister Charles Michel said he talked with Kerry about how “to do better (and) work together to be more efficient.”

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The terrorist cell behind the Paris and Brussels attacks is being wiped out but France is still being threatened, French President Francois Hollande said to journalists ahead of a meeting with former Israeli President Shimon Peres.

“The Paris attacks last year, Brussels, without forgetting what happened in Copenhagen, they all trace back to the troubles in Middle East, especially the war in Syria and Iraq,” he said.

Hollande said that despite arrests, the cell and other networks remain dangerous.

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Source: Man detained in Germany had revealing texts

In Giessen, a German town about 70 kilometers (43 miles) north of Frankfurt, police arrested a 28-year-old Moroccan man following a routine police check at a train station, a source briefed by German investigators told CNN.

The man, suspected of being connected to the Brussels attack cell, received a text message three minutes before the Brussels metro attack stating “Fin,” the French word for end.

Police sought out the man after they spotted him lingering on the platform with a bag, the source said. When they checked his passport they discovered he had been barred from the Schengen area, which allows for passport-free travel in 26 European countries, because of his involvement in robberies.

Authorities recovered some text messages from his phone. One of them had the name of Khalid El Bakraoui, the Brussels metro bomber. Another was sent to him at 9:08 a.m., three minutes before explosion, and stated simply “Fin.”

German investigators do not know who sent the message to him. Police also found a bill on his person from a Belgium hospital dated March 18 for treatment for injuries to his torso. German investigators believe it is possible the man was injured during a raid in Brussels last week, but have not firmly established this, the source said. They found documentation indicating he had recently traveled to Germany from Belgium, the source said.

Ten days ago, Belgian police exchanged fire with gunmen inside an apartment in Brussels. Several of those people inside, including Paris attack suspect Salah Abdeslam, escaped from the residence through the roof. Two, including Abdeslam, subsequently were taken into custody.

A second man arrested Thursday in Dusseldorf was also connected to El Bakraoui and his brother, Ibrahim, according to the source. German investigators have established the man took a flight from Amsterdam with Ibrahim El Bakraoui to Turkey last summer and was also arrested along with El Bakraoui in Gaziantep, near the Syria border.

Both men were deported back to Amsterdam on the same flight, the source told CNN.

Ibrahim and Khalid El Bakraoui were included in a U.S. counterterrorism watch list, a U.S. official familiar with the matter confirmed to CNN. Ibrahim El Bakraoui was on the list before the Paris attacks last November for his suspected ties to terrorism.

Khalid El Bakraoui was added after the Paris attacks because of his alleged involvement in helping to pay for a safe house for some attackers.

Abdeslam was interviewed for two hours by Belgian authorities on Saturday, Van Leeuw, Belgium’s federal prosecutor, said. Abdeslam has refused to answer questions in subsequent interviews, the prosecutor said.

Authorities have said Ibrahim El Bakraoui and ISIS bomb-maker Najim Laachraoui were killed in the blasts at the airport, and Khalid El Bakraoui on a train near the Maelbeek metro station.

Authorities are looking for two other men. One appears in surveillance footage holding a large bag at a Brussels metro station, according to Belgian public broadcaster RTBF. It is possible that he, like Khalid El Bakraoui, didn’t survive the subway blast.

The other is in another surveillance image wearing a hat and light-colored clothing alongside Laachraoui and Ibrahim El Bakraoui, with all three men rolling luggage carts through Brussels Airport.

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How to help victims of Brussels attacks

CNN’s Frederik Pleitgen reported from Brussels; Greg Botelho and Steve Almasy reported and wrote in Atlanta. CNN’s Nick Paton Walsh, Holly Yan, Catherine E. Shoichet, Mick Krever, Phil Black, Anna Maja Rappard, Paul Cruickshank, Margot Haddad and journalist Pierre-Eliott Buet contributed to this report.