A federal grand jury handed up an indictment Tuesday charging the man accused in a “calculated, targeted and unacceptably dangerous” attack last month at a New York City federal building with a single count of arson.

Former Army private Andrew Arrabaca “used a flammable liquid to ignite a fire at the Jacob K. Javits Federal Building in Manhattan, threw a firework into the fire that exploded, and lit fireworks at the Federal Building, causing injury to at least one person and substantial risk of injury to other persons, including federal employees, security guards and emergency personnel responding to the fire,” the indictment said.

Arrabaca has not yet entered a plea. An arraignment date was not immediately scheduled.

The attack on the lower Manhattan federal building was caught on surveillance cameras that showed a man in a helmet lighting fireworks, pouring gasoline onto a stairwell and lighting it and then firing a BB rifle before being tackled by a security guard.

Federal prosecutors have said Arrabaca began planning the July 20 attack in January when he traveled upstate to purchase a pellet gun and BB gun and to Pennsylvania to purchase fireworks.

They also said Arrabaca told investigators he considered other locations in the city before settling on a busy employee entrance at 26 Federal Plaza.