A man has killed two people and injured several others, one critically, in a knife attack in a town in south-east France.

Police arrested the man at about 11am after he had attacked customers in a shop and passersby at Romans-sur-Isère in the Drôme, 20km north of Valence.

Witnesses said the man first attacked the owner of a tobacconist and two customers inside the shop in the town centre. He then walked out and began stabbing people in the street. One of the dead was inside the tobacconist. A second man, a butcher from a nearby shop, was killed outside.

Police told French media the arrested man was a 33-year-old asylum seeker from Sudan. Anti-terrorism investigators have been advised and were said to be evaluating the situation before getting involved.

The suspect was living in the centre of the town where he carried out the attack. A statement from the local town hall read: “This Saturday 4 April morning an individual carried out a knife attack at several places in the centre of Romans-sur-Isère. The individual in question was arrested around 11am. According to initial information, two people have died, five others are injured and in a critical condition. At this moment, we do not know the motive for this act.”

Emmanuel Macron tweeted: “My thoughts go out to the victims of the attack in Romans-sur-Isère, the injured and their families. We will fully investigate this odious act that has added more grief to our country that has already suffered so much over the last few weeks.”