What we know about Sunday's knife attack in Paris

Seven people including two British tourists were wounded in north Paris late Sunday by a knife-wielding man. This is what we know about the attack so far.
What happened?
A man who was reportedly running with a knife about 25-30 cm (10-11 inches) long injured seven people including two British tourists on the banks of the Bassin de la Villette in the 19th arrondissement of the French capital. 
Four of the victims are in a critical condition, police have announced.
The terrifying attack saw bystanders trying to stop the assailant by throwing petanque balls at him. 
"There were around 20 people chasing him. They started throwing petanque balls at him," eyewitness Youssef Najah (28) said, referring to the sport popular in France also known as boules.
Photo: AFP
"Around four or five balls hit him in the head, but they weren't able to stop him," he added.
The suspect is believed to be an Afghan national and has been arrested, said a source close to the enquiry, adding he had targeted "strangers" but that "nothing at this stage shows signs of a terrorist nature".
What's it like in the area where the attack happened?
The area by Bassin de la Villette is not particularly touristy however it is popular with Parisians on sunny days and warm evenings. 
The neighbourhood has seen rising gentrification in recent years with a growing number of trendy bars and restaurants populating the streets near this part of the canal, as well as outdoor swimming pools in summer.
Parisians gather around the less touristy part of the canal to play petanque and other games, as well as for picnics and apero. 
There are also two cinemas on opposite sides of the canal. 
However there is another side to the area, which has proven to be a magnet for migrants and refugees and the location of huge squalid camps, the most recent of which was cleared in May.
Many refugees continue to congregate in the area, some to take part in English lessons given at the canal and others to get a warm meal served by charities. 
The area is also very popular with drug addicts. 
What do we know about the British victims?
According to reports in the French press, one of the British tourists has a chest injury while the other was stabbed in the head.
A man named Smain, who was one of the main people who helped stop the attacker, said that it was women's screams that alerted him to what was going on as he had at a drink at the nearby cafe. 
"He began to run, I grabbed my chair to hit him but he went to the other side of the road," he told the French press. "We started running after him with the young people throwing petanque balls.
The witness went on to describe how it was at this point that he crossed the path of two Englishmen. 
"The young people shouted "Watch out! Knife!" but the English did not understand what they were screaming... and he stabbed them," he said, adding that he hopes that the two people will survive. 
What is the UK doing?
The UK foreign office said it was aware of reports of the attack and was "urgently investigating this incident" in cooperation with French authorities, British media reported.
Was it terrorism?
Police have said that so far there is nothing to indicate that the incident was terrorism-related. 
Is there a rise in knife attacks?
A police investigation has been launched for attempted murder, according to a judicial source.
It is the latest of several knife attacks France has seen in recent months, with terrorism being ruled out in most cases.
On August 23, a man stabbed his mother and sister to death and seriously injured another person in a town near Paris before being shot dead by police.