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NICE, France — Two more suspects were detained for questioning early Sunday in connection with the Nice truck attack, officials said, amid lingering questions over whether the killer had accomplices.

The Paris prosecutor's office told NBC News that a man and a woman were taken into custody for questioning. That leaves six people still being held in wake of the bloodbath. A seventh, the attacker's ex-wife, was released from custody Sunday morning.

Flowers left on a road in Nice, France, on Saturday. VALERY HACHE / AFP - Getty Images

At least 84 people were killed and 200 injured when a truck driver mowed down revelers after a Bastille Day fireworks display Thursday.

The arrests come as new details emerged about attacker Mohamed Lahouaiej Bouhlel amid the ongoing investigation.

Bouhlel scouted out the Promenade des Anglais twice before the attack — on July 12 and 13, the prosecutor's office told NBC News. It said surveillance footage showed him in the truck he used to carry out the carnage.

Officials have said he wasn’t known to intelligence services. Interior Minister Bernard Cazeneuve told reporters Saturday that Bouhlel "appears to have become radicalized very quickly."

A close friend of Bouhlel's ex-wife, however, said he was not a radical Islamist but rather a violent man with nothing left to lose after his marriage fell apart.

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Anger continued to run high Sunday over the government's failure to thwart the third major attack in just over 18 months.

The Interior Ministry's move to call up reservists and ramp up security in the country, which has been under a state of emergency since the Paris attacks, was viewed by many as too little, too late.

One man with a poster on the Nice promenade drew applause as he shouted for the government to resign.

"Out, out" he cried. "Where were the politicians... on July 14?"

Anger at govt for perceived security failings. "Out! Out (Govt)! ... Where were the politicians... On July 14?" pic.twitter.com/qvmODoqaYK — Cassandra Vinograd (@CassVinograd) July 17, 2016

France was on the second of three days of national mourning on Sunday. The Promenade des Anglais — the scene of the carnage — was filled with flowers and tributes placed over blood stains on the pavement.

Blood still stains the pavement on the Promenade des Anglais pic.twitter.com/4Py1JXXapI — Cassandra Vinograd (@CassVinograd) July 17, 2016

Around 85 people remained hospitalized — with 18 in life-threatening condition, Health Minister Marisol Touraine said Sunday. Five children are among those in intensive care.

Only 35 of the dead had been formally identified as of Sunday, according to the Paris prosecutor's office, which said that all efforts were being made to complete the process as quickly as possible.

Several people also remain unaccounted for: photos of the missing were mixed with the condolences at memorials around the city.

One was of missing UC Berkeley student Nick Leslie. His family was expected to arrive in Nice on Sunday to search for the young man, according to NBC San Diego.

Still missing. Sunday in Nice. pic.twitter.com/WBfnmGVmlv — Cassandra Vinograd (@CassVinograd) July 17, 2016

All along the promenade people stopped to make the signs of the cross; many wiped away tears. From time to time, snippets of conversations could be heard among those who escaped the carnage, describing the horrors they had witnessed.

France's health minister joined calls for survivors to seek counseling in wake of the attack. The local children's hospital said it had seen 150 people it its psychological unit.

At the end of the long line of makeshift memorials, a shrine of a different sort was taking shape.

There were no flowers, just stones at the site where the attacker's murderous rampage ended due to a burst of police gunfire.

In the spot where his white truck finally stopped still, lit cigarettes burn and stones hold down angry messages: "savage assassin," read one. "Wild killer."

One man walking by pointed at the pile and sputtered the words echoed in writing on the rocks below: "burn in hell, son of a b***h."