Paris prosecutor Francois Molins holds a news conference at the Paris courthouse on June 26. He said there was no indication that a suspect held in an attack at a gas factory had an accomplice. (Stephane De Sakutin/AFP/Getty Images)

Following Friday’s attempted assault on a chemical plant that officials described as a terrorist attack, France was hunkering down Saturday for what politicians and analysts warned could be a prolonged period of uncertainty and fear.

Yassin Salhi, the 35-year-old delivery man who allegedly beheaded his boss and attacked a chemical plant near this city, was refusing to cooperate with police, authorities said.

But a clearer picture was emerging of his background, including suspected ties to an outlawed French Islamist group. Salhi also had reportedly associated with a French citizen who was wanted for questioning in the 2009 bombings of the Marriott and Ritz-Carlton hotels in Jakarta, Indonesia.

The attack, however, drove home the scope of the threat facing France. Five months after three homegrown extremists killed 17 people in and around Paris, officials, including Prime Minister Manuel Valls, were already warning the nation to brace for more terrorist attacks.

[Explosions hit French factory; terrorism probe opened]

Despite a number of steps taken to bolster counterterrorism and de-radicalization efforts here – including a sweeping surveillance law passed in recent days — analysts warned that the security problem confronting France outweighs the ability of the nation’s intelligence services to cope.

“We probably have 3,000 to 5,000 people in France who should be under surveillance,” said Jean-Charles Brisard, a counterterrorism expert based in Paris. “And we’ve got 3,000 people, a few more, doing that job. It’s just not possible to watch everyone.”

France, which is home to Europe’s largest Muslim population, has seen more of its nationals and legal residents — more than 1,200 — leave in recent years to join radical Islamists fighting in Syria and Iraq than have left from any other nation in the region. In April, Valls said that French authorities had, in recent months, foiled five terrorism plots.

On Friday, Salhi drove a delivery truck onto the grounds of an American-owned chemical factory. He drove into a shed, apparently trying to spark a large explosion. Only a minor blast occurred, and moments later, he was apprehended by a firefighter.

During his attack, Salhi placed the severed head of his boss on a fence post, along with flags carrying an Islamic declaration of faith. One question authorities were probing was whether Salhi had committed an independent act, or had taken direction or counsel from radical foreign or domestic groups.

Salhi had recently moved to the area, and officials were trying to establish whether he had purposely sought a job at the delivery firm because its trucks had access to the plant. During the attack, Salhi took a selfie with his boss’s severed head and sent it to a Canadian phone number, the Associated Press reported.

In Lyon, France’s third-largest city, which is known for sausages and fish dumplings, local residents spoke of a rising sense of insecurity.

“This could happen anywhere,” said Gérard Combe, 70, a local shop owner. “In airports, in malls, in crowded places. Is the state doing enough? It’s hard to say. The secret service are monitoring people, but it’s not enough.”

France is taking steps to strengthen its counterterrorism operations — sometimes, critics say, at the expense of civil liberties. On Wednesday, the Parliament passed a surveillance law allowing its intelligence services to collect vast amounts of Internet metadata and to eavesdrop on terrorism suspects without court orders. The controversial law, however, will not take effect until a court decides whether it is constitutionally sound.

In January, Valls announced that 2,680 counterterrorism positions would be created in the country’s security apparatus within the next three years. France has also sought to introduce more moderate imams into its prisons to combat radicalization behind bars.

But some here are pushing for far more controversial steps. On Saturday, Marine Le Pen — head of the far right National Front party — called for much more radical measures, including a freeze on the construction of mosques and the monitoring of Islamic sermons.

Some in France’s Muslim community voiced concern that growing fear of terrorism would empower those with a broader anti-Islamic agenda.

“In France, we feel isolated as Muslims,” said Elbagli Kadoug, 52, a maid who was waiting for a bus outside the suburban apartment building where Salhi lived with his family. “Now they will want to point the finger at us all.”

In addition to Salhi, his wife and sister also were in custody.

French officials had had Salhi under surveillance from 2006 to 2008, citing his association with known radicals. Because of lack of evidence, he faced a reduced level of scrutiny in recent years.

In 2014, French intelligence compiled a report on Salhi, according to one person briefed on the document. It noted that he had, in the past, been linked to the members of Forsane Alizza, a group whose leaders faced terrorism charges in court this month. Police raids of group members’ homes uncovered a cache of weapons and a list of alleged terrorism targets.

Virgile Demoustier contributed to this report.

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