Two people have been seriously hurt in a knife attack in Paris near the former offices of the satirical magazine Charlie Hebdo, officials say.
A suspect has been detained in the nearby Bastille area. A second suspect has also been arrested, reports say.
Anti-terrorism police have taken over the investigation.
A security cordon has been set up in the 11th arrondissement in eastern Paris. The public were told to avoid the area.
A blade – described as a machete or a meat cleaver – was recovered at the scene of the attack near the Boulevard Richard-Lenoir.
One of the arrested suspects was detained with blood on his clothing, a police source told the BBC.
Initial reports said that four people had been wounded.
The attack comes as a high-profile trial is under way in Paris of 14 people accused of helping two jihadists carry out the 2015 attack on Charlie Hebdo, in which 12 people were killed.
The two people wounded were staff at a TV production company, one of their colleagues told AFP news agency.
“Two colleagues were smoking a cigarette outside the building, in the street. I heard shouting. I went to the window and saw one of my colleagues, covered in blood, being chased by a man with a machete in the street,” another member of staff at the Premières Lignes production firm said.
The firm has offices in the Rue Nicolas Appert, a side street off Boulevard Richard Lenoir where the former Charlie Hebdo offices are located. A mural to the 12 people killed in the Charlie Hebdo attack is nearby.
The satirical magazine has since moved to a secret location.
Charlie Hebdo has marked the start of the trial by reprinting controversial cartoons of the Prophet Muhammad that sparked protests in several Muslim countries.
In response, the militant group al-Qaeda renewed its threat to the magazine.
The defendants in the trial are also accused of helping another jihadist carry out a related attack in which he shot dead a policewoman, then attacked a Jewish store, killing four people.
The 17 victims were killed over a period of three days. All three attackers were killed by police. The killings marked the beginning of a wave of jihadist attacks across France that left more than 250 people dead.