NICE, France (AP) — The Latest on the truck attack in Nice on Bastille Day that killed 84 people: (all times local):

4:40 p.m.

U.S. Secretary of State John Kerry says the challenge of finding and stopping people like the truck driver who plowed into a crowd at Bastille Day festivities in the French city of Nice is “worse than the needle in the haystack.”

Kerry says the U.S. had no knowledge of the killer as a radicalized individual and that if someone is an extremist of “one or two days vintage” it’s easy to cause mayhem.

Kerry, appearing on CNN, says the attack shows the Islamic State group is under great pressure, and that people are acting out in various places. He says the group sees “the noose closing around them.”

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2 p.m.

A French official in the Paris prosecutor’s office says the estranged wife of truck driver Mohamed Lahouaiej Bouhlel — who killed 84 people on a Thursday night rampage in Nice — has been released from custody.

The woman was released Sunday. She is the mother of Bouhlel’s three children, and was in the process of divorcing him. She was arrested Friday, a day after the 31-year-old Tunisian plowed through revelers out to see the Bastille Day fireworks on Nice’s famed seaside boulevard.

Investigators hunting for possible accomplices to Bouhlel arrested two people Sunday. In total, 6 people remain in custody relating to the attack that IS has claimed.

— By Thomas Adamson in Paris.

1:05 p.m.

French authorities say they still haven’t identified 16 of those killed and one person wounded in the Bastille Day truck attack in Nice.

The government says 84 people were killed and 202 injured in the attack Thursday night, including many tourists from multiple countries.

An official with a special victims’ center in Nice told reporters Sunday that 16 bodies remain unidentified, and forensic experts are working with DNA samples to determine their identities. The official did not give his name.

Health Minister Marisol Touraine said Sunday that one hospitalized person remains unidentified. In all, 85 people are still hospitalized after the attack, 18 of them in critical condition.

Many family members have been frustrated by a lack of information about their missing loved ones.

—Adam Pemble in Nice.

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12:55 p.m.

Pope Francis has prayed for the end of “terror and death” of innocents as he expressed closeness to families and all of France mourning the loss of lives, “even of many children,” in the Nice truck attack.

Francis told the public in St. Peter’s Square on Sunday that “sorrow is great in our hearts” for the massacre in the southern French city last week, and prayed that God sustain the wounded and comfort relatives.

He prayed that God “disperse every plan for terror and for death, so that no man dare spill more blood of his brother.”

Francis then offered “a paternal and fraternal embrace for all of Nice’s inhabitants and all of France,” and invited those in the square to join him in silent prayer for the 84 Nice victims and their families.

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12:25 p.m.

France’s prime minister says the Islamic State group could have been responsible for last week’s Bastille Day attack on Nice.

Manuel Valls, in an interview with the Journal du dimanche newspaper published Sunday, said the Islamic State group “is encouraging individuals unknown to our services to stage attacks.” While the investigation is working on details, he said “that is without a doubt the case in the Nice attack.”

IS claimed responsibility for Thursday’s truck attack that killed 84 people, but neither the extremist group nor the French government has provided concrete signs of an IS link with the driver. Valls said only that authorities “now know that the killer radicalized very quickly.”

Valls also warned that “terrorism will be part of our daily lives for a long time.”

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11:45 a.m.

France’s health minister says about 85 people remain hospitalized after a deadly truck rampage in the Mediterranean city of Nice, and 18 of them are in life-threatening condition — including one child.

Health Minister Marisol Touraine urged any survivors to seek counseling offered by the government after the Bastille Day attack Thursday night that killed 84 people.

Speaking to reporters in Nice on Sunday, Touraine said while scores of people who were hospitalized have been released, some may need further medical treatment as their injuries heal.

The Islamic State group has claimed responsibility for the attack by a local Nice truck driver who was killed by police.

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11:15 p.m.

French authorities have detained two more people in the investigation into the Bastille Day truck attack on the Mediterranean city of Nice that killed at least 84 people, as authorities try to determine whether the slain attacker was a committed religious extremist or just a very angry man.

A man and a woman were detained Sunday morning in Nice, according to an official with the Paris prosecutor’s office, which oversees national terrorism investigations. The official provided no details on their identities, and said five people detained previously remain in custody. Neighbors told The Associated Press that the attacker’s estranged wife was among them.

Investigators are hunting for possible accomplices to truck driver Mohamed Lahouaiej Bouhlel, a 31-year-old Tunisian who had lived in Nice for years. He was killed by police after ramming his truck through crowds on Nice’s famed seafront after a holiday fireworks display Thursday night.

The Islamic State statement said Bouhlel was following their calls to target citizens of countries fighting the extremists, but it’s unclear whether he had concrete links to the group.

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10 a.m.

Nice’s famed Promenade des Anglais is gradually reopening and becoming a shrine to the dead, with memorials set up on the westbound lane of the road where victims were felled by an attacker with a truck. Some spots are still identifiable by bloodstains.

Joggers, bikers and sunbathers on Sunday cruised along the pedestrian walkway along the glistening Mediterranean Sea, where well-wishers placed flowers, French flags, stuffed animals and candles.

The site is also becoming a platform for anger at the attacker. Pained and outraged epitaphs are now written in blue maker on stones placed where police shot him dead.

Many families are angry that they couldn’t find information about missing loved ones, and many are angry at police for not preventing the deadly attack despite France being under a state of emergency imposed after Islamic State attacks last year in Paris.