PARIS — The French authorities on Thursday identified a second man who stormed a church in Normandy and killed an 85-year-old priest as he celebrated Mass.

The Paris prosecutor’s office identified the man as Abdel-Malik Nabil Petitjean, 19. It was not clear how he knew the other killer, Adel Kermiche, also 19, who lived near the church, the Église St.-Étienne, in St.-Étienne-du-Rouvray, a working-class suburb of Rouen.

Both were of Algerian ancestry. They were shot dead by the police after the assault on the church on Tuesday, which also left an 86-year-old parishioner severely wounded; he is in stable condition.

The Islamic State released videos on Wednesday in which the two young men pledged allegiance to the terrorist group before the assault, which killed the Rev. Jacques Hamel.