Police look into whether Chérif Chekatt, who killed four, had accomplices, as one of the victims of the attack is buried

French authorities are working to clarify why the suspect in the Strasbourg Christmas market attack was not stopped before he could act, Emmanuel Macron has said, as police investigate whether there were any accomplices.

Chérif Chekatt killed four people and wounded several others in Tuesday’s attack, after police had tried and failed to arrest him earlier in the day. The 29-year-old had been known to police for theft and violence dating back to the age of 10 and had been on a French intelligence watchlist for radicalism.

He was shot dead by police in Strasbourg on Thursday night after a 48-hour manhunt.

Macron said in Brussels on Friday that France should “draw from the consequences” of any police failures and work on “what could be improved”.

Rémy Heitz, a French prosecutor, said that after a two-day manhunt by more than 700 officers, three local police officers patrolling in the Neudorf area of Strasbourg on Thursday night saw a man corresponding to Chekatt’s description. He is believed to have been wearing a long, black winter coat as he stood near a building on a residential street.

Chekatt noticed the marked police car and tried to enter a building. When the officers shouted “police”, he turned around and opened fire at them.

“A projectile hit the police vehicle above the left rear door. Two police officers responded, shooting several times, and killed him,” the prosecutor said.

Facebook Twitter Pinterest Christophe Castaner, France’s interior minister, talks to the press at the reopening of the market on Friday. Photograph: Sébastien Bozon/AFP/Getty

Investigators found a gun, a knife and ammunition on Chekatt’s body. One gun corresponded to descriptions of the gun used in the shooting on Tuesday night. The Paris prosecutor’s office later formally identified the man as Chekatt and said he had died at the scene at 9.05pm.

The prosecutor said investigators had focused their search on the Neudorf area of Strasbourg in part owing to witness information. An appeal for witnesses led to about 800 calls, many of which were “decisive”, including one from a man who had seen the suspect jumping over a gate. Police had lost track of Chekatt in Neudorf on Tuesday night after the shootings in the city centre.

The prosecutor said seven people were in police custody, including four of Chekatt’s family members. Three of his entourage were also arrested, one on Thursday morning and one overnight.

Police are looking at whether Chekatt had help preparing his attack and whether he was assisted or sheltered during his two days hiding from police.

On Friday the funeral was held for one of the victims of the attack. Kamal Naghchband, 45, fled Afghanistan about 20 years ago to build a new life in France. “He was going to see the Christmas market and – in front of his children – he took a bullet,” one of his cousins said.

Facebook Twitter Pinterest People carry the coffin of Kamal Naghchband, who was killed in the Strasbourg attack. Photograph: Patrick Hertzog/AFP/Getty Images

Chekatt was well known to police. He received his first conviction at 13, and had 26 more. He served jail time in France, Germany and Switzerland.

For the past two years he had been under surveillance as a potential security risk after the French prison services raised questions about suspected radicalisation in jail.

France’s interior minister, Christophe Castaner, on Friday dismissed a claim by Islamic State that it was responsible for the Strasbourg attack.

Castaner described as “completely opportunistic” a Twitter post by the propaganda wing of Isis, which claimed that Chekatt was one of its “soldiers”. Castaner said: “We’re dealing with a man who was consumed by evil.”