Saturday, a U.S. grand jury indicted a man on terrorism and other counts coming from a shooting and smoke bomb incident on the New York City subway on April 12 that injured 23 people.

In the indictment filed in the U.S. District Court for the Eastern District of New York, Frank James, 62, was charged with a terrorist attack and other violence against a public transit system and firing a firearm during a violent felony.

James may face life in jail if found guilty of the terrorism allegation.

James's defense counsel did not immediately reply to calls for comment.

James is accused of detonating smoke bombs and opening fire inside a New York City subway car in Brooklyn, wounding ten others with gunshots, and sparking a 24-hour search.

According to officials, thirteen people were injured in the panicked scramble to escape the smoke-filled train.

He was apprehended some 30 hours later in lower Manhattan, some 8 miles (13 km) from the assault scene, after officials discovered his whereabouts with the help of information from people, some of whom reported sightings on social media, according to police.

James, a native of the Bronx with recent homes in Philadelphia and Milwaukee, was previously charged with a criminal complaint related to the assault. The formal indictment followed the presentation of evidence to a grand jury by prosecutors.

Authorities accuse James of detonating two smoke bombs inside a subway car moments before opening fire with a semiautomatic handgun on fellow passengers. The 2011-purchased firearm, along with three extended-ammo magazines, a torch, a hatchet, a bag of fireworks, and a container of gasoline, were later discovered at the site, according to police and court filings.

The attack followed a succession of violent crimes that unnerved travelers in the most extensive urban transit system in the United States, including incidents in which commuters were shoved down subway lines from station platforms.

The motivation remained obscure. In an FBI document, James' YouTube videos addressing the mayor of New York City about homelessness and the subway system were referenced.