The gunman who shot dead a policeman in Paris on Thursday has been identified from papers left in his car, but French officials are yet to release his name.
Local media say the 39-year-old lived in the city's suburbs, and had been seen as a potential Islamist radical.
The gunman wounded two police officers before being shot dead by security forces on the Champs Elysees.
A pump-action shotgun and knives were found in his car, the French TV station BFMTV reports.
French media named the man as Karim Cheurfi, 39, from the eastern Paris suburb of Chelles.
Another man suspected of possible links to the attack has turned himself in to Belgian police.
French police have detained three members of the gunman's family, Reuters news agency reports, citing a legal source.
Prime Minister Bernard Cazeneuve said security forces, including elite units, were fully mobilised ahead of Sunday's presidential election.
"Nothing must be allowed to impede the fundamental democratic process of our country," he said after an emergency security cabinet meeting.
So-called Islamic State (IS) has said one of its "fighters" carried out the attack.
On Friday the main candidates were quick to urge tough action against Islamist terrorism but cancelled the final rallies they had planned.
Mr Cazeneuve, a Socialist, accused two of the frontrunners - far-right candidate Marine Le Pen and conservative François Fillon - of exploiting the attack for electoral gain. He scorned Ms Le Pen for linking the attack to immigration.
The shooting is a shocking event that will certainly be on voters' minds on Sunday, the BBC's Hugh Schofield in Paris says.
What happened on the Champs Elysees?
A car pulled up alongside a police bus just before 21:00 (19:00 GMT) and a man got out, opening fire on the bus with an automatic weapon, Interior Ministry spokesman Pierre-Henry Brandet said.
After killing an officer, the man attempted to run away while shooting at other officers, two of whom he injured, the spokesman added.
He was then shot dead by security forces.
Terrified eyewitnesses later recounted scenes of panic as they ran for cover after hearing gunfire.
The whole of the Champs Elysees was evacuat.
BBC
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