Serving at a juice bar at an unusually quiet central Saint-Lazare train station, 24-year-old Parisian student Laura Stern admitted to being “a little bit scared” a day after the worst attack on the capital in decades.

But the attack by suspected Islamist militant gunmen who killed 12 people at the office of a satirical weekly on Wednesday – followed by the still unexplained killing of a policewoman in a shootout in southern Paris yesterday morning – didn’t stop her going to work.

“People here keep coming up to me to say: be careful,” said Stern, who works at the bar to finance her studies. “But that’s not a reason to stay at home.”

Minutes later, a police mine-clearing squad in full gear swooped in after being alerted to a suspect package.

The deadly shootings of the past two days were on everybody’s lips in Paris and security was visibly tightened, with dozens of extra patrols by police and soldiers.

Another train station, the Gare du Nord, was briefly evacuated and several metro lines were disrupted to allow security checks.

The metro stopped for a minute at midday and all fell silent in memory of the dead in offices, schools and public buildings all over the city.

At the sprawling Jussieu university in central Paris, metallic gates usually closed only at night were drawn up. Fewer entrances were accessible than usual, said one guard.

In the library, screens showing university messages regularly switched to “Je suis Charlie” (“I am Charlie”), an omnipresent slogan in social media, public billboards and rallies in solidarity with the attacked Charlie Hebdo newspaper.

“We talk about it a lot ... But then, day-to-day life does not change much. We do our work as usual,” 26-year-old math student Nalo Magalhou said.

Out front, newspaper kiosk vendor Ali said he had run out of most papers in an unprecedented rush of customers.

“I’ve sold everything, even the foreign newspapers,” he said, showing the empty shelves after disappointing a woman looking for a copy of Le Figaro.

At Porte d’Orleans, one of the main entry points to Paris, more than a dozen white police vans lined up the main avenue. A few officers stood guard with bulletproof jackets and rifles.

Sports gym manager Fabrice Lesniarek said he felt reassured by their presence.

A few miles away in central Paris, 41-year-old cab driver Julien Battiste said his clients were saddened but combative.

“What I’ve seen here in my taxi is that Parisians want to stay strong and keep going to protect our freedom of expression and democracy,” he said.