Paris attacks: French authorities make 10 arrests, net also cast to Belgium

he Paris prosecutor's office says 10 people have been 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 of Iraq and Syria (ISIS).

Spokeswoman Agnes Thibault-Lecuivre says the arrests began overnight and continued in three towns Friday morning.

Authorities are on high alert in France and neighbouring Belgium , where authorities moved swiftly Thursday night to pre-empt what they called a major impending attack.

The prosecutor's office says Friday's raids around Paris are linked to Amedy Coulibaly , one of three gunmen involved in France's worst terrorist attacks in decades.

Authorities in France and several countries are looking for possible accomplices.

In Paris, police say the Gare de l'Est train station has been closed and evacuated after a bomb threat, as authorities try to prevent new violence after the worst terrorist attacks in decades.

A police official says the station was closed "as a precaution." The official, who was not authorized to be publicly named, would not give further details.

The Gare de l'Est is one of several major train stations in Paris, serving cities in eastern Paris and countries to the east.

U.S. Secretary of State John Kerry, meanwhile, is in the city meeting top officials in France to express America's solidarity with the French people after last week's deadly terrorist attacks.

French President Francois Hollande, left, greets U.S. Secretary of State John Kerry as he arrives for a meeting at the Elysee Palace in Paris. (Ian Langsdon/EPA)

"I think you know that you have the full and heartfelt condolences of the American people and I know you know that we share the pain and the horror of everything that you went through," Kerry said as he greeted French President Francois Hollande Friday. "Our hearts are with you."

Kerry was seeing Hollande and Foreign Minister Laurent Fabius Friday morning before laying wreaths at the sites of the two attacks. Kerry will then join the mayor of the city at an event that is to include a short performance by musician James Taylor.

Kerry's visit comes amid lingering criticism of the Obama administration's failure to send a cabinet-level official to Paris for last Sunday's unity march that attracted some 40 world leaders and more than a million demonstrators.