Paris police evacuated the Gare de l'Est train station Friday after a bomb threat, as authorities across Europe pressed on with efforts to prevent new violence after the worst terrorist attacks in decades.
The Paris prosecutor's office, meanwhile, said 12 people were arrested in anti-terrorism raids in the region, targeting people linked to a gunman who attacked a kosher supermarket and claimed ties to the Islamic State.
The developments, coming on the day that U.S. Secretary of State John Kerry arrived to "share a big hug with Paris," came a day after Belgian police killed two suspected terrorists in a firefight and arrested a third man.
A French police official said the Gare de l'Est station was closed "as a precaution." The official, who was not authorized to be publicly named, would not give further details. The station, one of several main stations in Paris, serving cities in eastern Paris and countries to the east.
In Berlin, police arrested two men Friday morning on suspicion of recruiting fighters for the so-called Islamic State group in Syria.
Belgian authorities say 13 people have been detained in Belgium and two arrested in France in an anti-terror sweep following a firefight in which two suspected terrorists were killed.
Eric Van der Sypt, a Belgian federal magistrate, said Friday that a dozen searches had led to the discovery of four military-style weapons including Kalashnikov assault rifles.
Belgian police on Thursday moved in on a suspected terrorist hideout in the eastern city of Verviers, killing two suspects and wounding and arresting a third.
Sypt says the terrorists' goal was to kill police on the street or in their offices.
The Belgian raid on a former bakery was another palpable sign that terror had seeped deep into Europe's heartland as security forces struck against militants some of who may be returnees from Islamic holy war in Syria. Federal magistrate Eric Van der Sypt said returnees were an important part of the targeted searches.
After the gun smoke lifted, police continued with searches in Verviers and the greater Brussels area, seeking more clues in a weeks-long investigation that started well before the terrorism spree last week that led to 17 deaths in the Paris area. The Belgian operations had no apparent link to the terrorist acts committed in France.
And, unlike the Paris terrorists, who attacked the office of a satirical newspaper and a kosher grocery store, the suspects in Belgium were reportedly aiming at hard targets: police installations.
"They were on the verge of committing important terror attacks," Van der Sypt told a news conference in Brussels.
Belgian authorities had moved swiftly in the rustbelt town of Verviers Thursday to pre-empt what they called a major attack by as little as hours.
"As soon as I opened the window, you could smell the gunpowder," said neighbor Alexandre Massaux following a minutes-long firefight with automatic weapons and Kalashnikovs that was also punctuated by explosions.
"As soon as they thought special forces were there, they opened fire," federal magistrate Van der Sypt said.
Across Europe, anxiety has grown as the manhunt continues for potential accomplices of the three Paris terrorists, all of whom were shot dead by French police. Authorities in Belgium signaled they were ready for more trouble by raising the national terror alert level from 2 to 3, the second-highest level.
"It shows we have to be extremely careful," Van der Sypt said. The Verviers suspects "were extremely well-armed men" equipped with automatic weapons, he said. Some of the individuals "were in Syria and had come back," he added.
Authorities have previously said 300 Belgian residents have gone to fight with extremist Islamic formations in Syria; it is unclear how many have returned.
The suspects in Verviers opened fire on police when they closed in on them near the city's train station, the magistrate told reporters. Video posted online showed a dark view of a building amid blasts, gunshots and sirens, and smoke billowing up from a fire.
No police were wounded or killed in the clash, which occurred at the height of rush hour in a crowded neighborhood of this former industrial town of 56,000 about 80 miles southeast of the capital, Brussels.
Earlier Thursday, Belgian authorities said they were looking into possible links between a man they arrested in the southern city of Charleroi for illegal trade in weapons and Amedy Coulibaly, who killed four people in a Paris kosher market last week.
The man arrested in Belgium "claims that he wanted to buy a car from the wife of Coulibaly," Van der Sypt said. "At this moment this is the only link between what happened in Paris."
Several other countries are also involved in the hunt for possible accomplices to Coulibaly and the other gunmen in the French attacks, brothers Cherif and Said Kouachi.
The Kouachi brothers claimed allegiance to al-Qaida in Yemen, and Coulibaly to the Islamic State group.
In Spain, authorities said Coulibaly drove his common-law wife from France to Madrid on Dec. 31 and was with her until she took a Jan. 2 flight to Istanbul.
Spain's National Court said it was investigating what Coulibaly did in the country's capital with his wife, Hayat Boumeddiene, and a third person who wasn't identified but is suspected of helping Boumeddiene get from Turkey to Syria.
France is on edge since last week's attacks, which began at the satirical newspaper Charlie Hebdo. The paper, repeatedly threatened for its caricatures of the Muslim Prophet Muhammad, buried several of its slain staff members Thursday even as it reprinted another weekly issue with Muhammad on its cover.
Defense officials said France came under an unprecedented cyber assault with 19,000 cyberattacks launched after the country's bloodiest terrorist attacks in decades, frustrating authorities as they try to thwart repeat violence.
The attacks, mostly relatively minor denial-of-service attacks, hit sites as varied as military regiments to pizza shops but none appeared to have caused serious damage.