(Reuters) – A U.S. grand jury on Saturday indicted a suspect for terrorism, among other charges, stemming from the April 12 gunfire/smoke bomb attack on New York City’s subway that left 23 people injured.

Frank James (62), was indicted by the U.S. District Court for Eastern District of New York for terrorist attack, other violence against mass transportation systems, and discharging firearms during a crime of force.

James could receive a life sentence if convicted for the terrorist offense.

James was not immediately contacted by James defense lawyers for comment.

James is charged with setting off smoke bombs in a New York City subway train station. He also set fire to a New York City apartment.

According to police, thirteen other people were also injured during the panicked rush for safety from the fume-filled train.

After authorities received tips from local residents who posted sightings via social media on his location, he was arrested in Manhattan about 30 hours later.

James is a Bronx native who has recently been to Philadelphia and Milwaukee. A criminal complaint was filed earlier by law enforcement regarding the attack. After prosecutors gave evidence to the grand jury, James was indicted more seriously.

James is accused of setting off smoke bombs in a subway car before opening fire with his semi-automatic pistol on other passengers. According to court records and police, the gun was purchased in 2011. It was then recovered along with three magazines of extended ammunition, a torch and a hatchet. A bag of fireworks, as well as a gasoline container, were all found on the spot.

This attack came after a string of violent crimes that disturbed passengers of America’s most populous metropolitan transit system. There were also instances when commuters were pushed onto the subway tracks by station platforms.

It was not clear what the motive behind this incident was. The FBI referenced a variety of YouTube videos James uploaded to address statements to New York City’s Mayor regarding homelessness, and the subway system.