At least two people were killed Thursday in an anti-terrorism operation near a train station in the eastern Belgian city of Verviers as authorities widened their investigation into last week's terrorist attacks in France to include potential accomplices in Belgium and Spain.
The night raid in Verviers was part of a counter-terrorist operation against Islamist groups in several locations in Belgium on Thursday during which two people died in a shootout with police and a third was injured, Mayor Marc Elsen confirmed to Radio Télévision Belge Francophone, or RTBF.
During the raid, gunfire and several explosions could be heard, RTBF reported.
The Belgian federal prosecutor's office said that the suspects in Verviers "immediately opened fire with automatic weapons" as police attempted to serve the search warrant.
They fired on officers for several minutes before "being neutralized," said Eric Van der Sypt, a spokesman for the prosecutor's office.
No police or civilians were harmed during the operation and no suspects got away, he said. The injured suspect was in custody.
Special counter-terrorism police forces are executing about 10 search warrants at the request of the federal prosecutor's office in Brussels, Verviers and Vilvoorde. These were executed as part of an investigation "concerning several people who we think are an operational cell," including some who had just returned from Syria, said Van der Sypt, who added that the suspects had planned an imminent attack in Belgium.
He declined to say what they were doing in Syria and when they had returned. Investigation began "a few weeks ago, before the attacks in Paris," he said. It was not immediately clear if Thursday's raid was connected with last week's violence in Paris.
Verviers is about 70 miles east of Brussels and 200 miles northeast of the French capital.
Belgian authorities were also trying to determine Thursday whether a man detained in the southern city of Charleroi for arms trafficking was linked to Amedy Coulibaly, one of the Paris attackers. Coulibaly, 32, was killed by French police Friday after he took hostages at a Paris kosher grocery store, killing four of them.
Coulibaly traveled to Charleroi several times in late November or early December last year, according to RTBF.
He came to sell his girlfriend's car, a Mini, according to the man he sold it to, Neetin Karasular, who turned himself in to authorities, RTBF reported.
Karasular acknowledged knowing Coulibaly and meeting him repeatedly in Charleroi. Karasular denied selling the attacker weapons, and his attorney told RTBF the Belgian acted only as a go-between for the car sale.
Spanish anti-terrorism agencies were also trying to determine whether their nation is home to a terrorist support cell. Seventy Islamist fighters returned to Spain last year from conflict zones, according to the Spanish newspaper La Vanguardia.
Officials at Spain's high court said Thursday that they had opened an investigation into the time Coulibaly apparently spent there during the last month with his girlfriend, Hayat Boumedienne.
Investigators have determined that the pair stayed in Madrid from Dec. 30 to Jan. 2, accompanied by an unidentified man, according to La Vanguardia.
French authorities reportedly are searching for a fourth suspect in connection with the Paris attacks.
Coulibaly had rented a house in suburban Gentilly, south of Paris, the week before the attacks and filled it with a stockpile of weapons and equipment that investigators used to identify the fourth suspect, according to the newspaper Le Parisien.
A search of the small house by detectives from the Paris Criminal Brigade and a special police anti-terrorism unit resulted in the seizure of the key to a scooter that allowed them to identity the new potential accomplice, according to French police union spokesman Christophe Crepin.
In the Gentilly house, investigators also recovered the keys to a car, radical Islamist documents and a flag from the militant group Islamic State, Le Parisien reported.
The newspaper did not identify the suspect, but said he may have shot and seriously wounded a jogger in the Paris suburb of Fontenay-aux-Roses on Jan. 7, the same day that two friends of Coulibaly, brothers Cherif Kouachi, 32, and Said Kouachi, 34, killed a dozen people at the offices of satirical magazine Charlie Hebdo.
The fourth suspect may have been involved in the attack on the magazine, has a lengthy criminal record and could have already fled to Syria, Le Parisien reported.
Police believe that the suspect has a record for white-collar crime, is from Seine Saint Denis northeast of Paris, and fits the description provided by the wounded jogger, according to Le Parisien.
Police had previously said Coulibaly was suspected of wounding the jogger. He also has been accused of killing a French policewoman last Thursday.
Crepin said he could not confirm the reports that police were seeking a new suspect, but that the three gunmen in the Paris attacks did not act alone and received weapons from Brussels. He said they also received two rocket launchers, but would not say whether investigators have traced the weapons to terrorists or a particular country.
He said the organization backing the trio was "mafia-like."
"The financing was by a jihadist cell," he said. "When you see the financing and the determination -- these men were at war. That's just it -- we are at war now."
Al Qaeda in the Arabian Peninsula, which is based in Yemen, released a video Wednesday claiming responsibility for the Charlie Hebdo attack. Crepin said police believe that the attackers did not have the resources to pay for the weapons, ammunition and equipment used in the assault, or to rent suspected hideouts on their own, but he could not say whether Al Qaeda was behind it.
A regional French newspaper found documents showing that before the attack, Coulibaly received a loan of 6,000 euros, about $7,000, from a company based in northern France. In a video released last weekend, Coulibaly said he had given the Kouachi brothers several thousand euros to pay for their supplies.
Investigators on Thursday reportedly were still trying to track down Mehdi Belhoucine, 23, who was seen fleeing with Boumeddiene, Coulibaly's 26-year-old girlfriend, in security camera images captured at Istanbul's airport on Jan. 2. Belhoucine's older brother was sentenced to a year in prison last year for recruiting fighters for Afghanistan and Pakistan.
Turkish officials have said Boumeddiene crossed from Turkey into Syria, but it was not clear Thursday whether Belhoucine was with her.
According to Le Parisien, police are still searching for a black Mini Cooper registered to Boumeddiene.
Earlier this week, Bulgarian authorities jailed another suspect in connection with the attacks: Joachim Fritz-Joly, 28, a friend of Cherif Kouachi who was on his way to Turkey and is now being held pending a hearing to determine whether he can be extradited to France.
Meanwhile, the head of cyberdefense for the French military said Thursday that hackers have targeted about 19,000 French websites since last week's attacks.
The official, Adm. Arnaud Coustilliere, called the hacking an unprecedented surge, though most incidents involved relatively minor denial-of-service attacks, the Associated Press reported. They hit sites as varied as military regiments to pizza shops but none appeared to have caused serious damage, he said.
Also Thursday, Parisians again lined up before dawn and waited hours in the cold for the second day of sales of Charlie Hebdo's latest edition, the first since the attacks, featuring a caricature of the prophet Muhammad on the cover under the headline "All is Forgiven."
Friends and family paid their respects to cartoonists Bernard "Tignous" Verlhac and Georges Wolinski, as well as a columnist and a policeman killed in the attacks.
Scores of mourners could be seen on BFM gathering outside a private funeral service for Verlhac, 57, in the Paris suburb of Montreuil ahead of his burial at Pere Lachaise cemetery, the famous resting place of writers, artists and composers.
As his coffin arrived at town hall for the service, covered with drawings and messages from supporters, the crowd applauded.
U.S. Secretary of State John F. Kerry arrived in Paris late Thursday, pledging "to share a big hug with Paris" as the first Obama administration official to visit since the attacks. He was expected to attend a town hall meeting Friday with the Paris mayor and American musician James Taylor, who is scheduled to perform.
Times staff writer Christine Mai-Duc in Los Angeles contributed to this report.