French police work at the site of a knife attack in the neighborhood of the Opera in Paris May 13, 2018. A man randomly attacked bystanders with a knife on Saturday night in central Paris, Paris prefecture confirmed. (Xinhua/Theo Duval)

PARIS, May 13 (Xinhua) -- A friend of the Paris knife attacker who has been shot dead by French police after having killed a stand-by on Saturday night in Paris has been arrested and held for questioning on Sunday in the French city of Strasbourg, according to French media.

The arrested was born in 1997, the same as the attacker, French channel BFMTV reported.

This is the third arrest since the attack happened. The attacker's father and mother have been held for questioning earlier by police on Sunday ,according to the same source.