Slain Teen Behind Attack on German Train Apparently Left Pro-ISIS Video

— -- The knife- and ax-wielding teenager who’s accused of attacking passengers on a German train apparently left a pro-ISIS video in which he pledged to carry out an operation in Germany, according to a translation provided by the SITE Intelligence Group.

At least five people were injured in the Monday night attack near Wuerzburg, according to The Associated Press. Police shot and killed the 17-year-old Afghan boy, authorities said.

The attacker's name has not been released by authorities.

Someone was heard shouting "God is great" in Arabic during emergency calls to the police during the attack, authorities added.

ISIS claimed responsibility for the attack and ISIS’ Amaq news agency released a two-minute, 20-second video today that allegedly shows the attacker, according to the Maryland-based SITE Intelligence Group, a private firm that monitors extremists’ online activity.

The person in the video message said, according to a translation from SITE, that soldiers of the Islamic Caliphate will target people where they live and work.

The translated video also mentioned use of a knife and axes.

The Bavarian state criminal office said it is checking the authenticity of the video.

Lothar Köhler, head of the Bavarian Landeskriminalamt criminal division, said the suspected attacker came to Germany in June 2015 as an unaccompanied minor. He was granted refugee status in March of this year and housed with a foster family two weeks ago, Köhler said.

He was a practicing Sunni Muslim, Köhler said. About 24 hours before the attack, he published a post about "the enemies of Islam," Köhler said, and a hand-drawn symbol of Islamic State was found in his room.

The Bavarian state criminal office said the attacker was not previously known to police or on any watch lists.

ABC News’ Josie Le Blond contributed to this report.