Bill Killian, U.S. attorney for the east district of Tennessee, left, describes how Colton Partin, James Smiley and Kyle Montgomery fired mortar-style fireworks at East Lake residents during a news conference in the U.S. attorney's office. The three Chattanooga men pleaded guilty to civil rights charges in federal court on Friday.

Colton Partin, James Smiley and Kyle Montgomery

Three men who pleaded guilty Friday to federal charges that they conspired to launch fist-sized fireworks at black residents of public housing will be sentenced on April 12.

Colton Partin, 21, of Apison; James Smiley, 27; and Kyle Montgomery, 21, of Chattanooga, each pleaded guilty to conspiracy against rights before U.S. Magistrate Judge Susan Lee.

Friday afternoon U.S. Attorney Bill Killian held a news conference in his office lobby about the investigation and guilty pleas.

"We will aggressively address and prosecute civil rights matters, regardless of the source or nature of the circumstances, or the race, religion, ethnicity, sexual orientation, or any other classification of the victims," Killian said.

Between 3:30 a.m. and 4 a.m. on July 9, Partin drove a pickup truck with Montgomery and Smiley as passengers through East Lake Courts public housing.

The trio fired "mortar-style fireworks, from a cylinder" directly toward a group of five black residents on the porch of one of the apartments.

The victims scattered to avoid being struck, and one of the fireworks shattered a window pane in the apartment of a woman asleep with her infant child and boyfriend's juvenile siblings, according to court documents.

"It was a horrible crime, inflicted with stunning disregard for the lives and safety of the victims," FBI Special Agent-in-Charge Rick Lambert said during the news conference.

"Most troubling, however, is the fact that this incident harkens back to the darkest ages of our nation's history," Lambert said.

In sentencing before U.S. District Judge Curtis Collier, the men face a punishment as low as probation or as high as 10 years in prison.

Though prosecutors wouldn't comment about the likely punishment, a brief exchange between Lee and Assistant U.S. Attorney Chris Poole hinted at a possible range of punishment.

Lee was concerned that if detained until sentencing the defendants could actually serve more time in jail than what they eventually would be sentenced to by the court.

Poole, consulting with U.S. Department of Justice civil rights division attorney Myesha Braden, told Lee that under the range and criminal history record Montgomery could face about six months in prison.

After a more than two-hour hearing Lee ruled that Partin and Smiley could remain free awaiting sentencing. Montgomery was detained.

Federal law requires those who plead guilty to a violent crime be held pending sentencing unless there is an extraordinary circumstance, Lee said in court.

Partin is undergoing mental health treatment for a diagnosed anxiety disorder and assists his father who is recovering from a recent surgery that limits his physical abilities.

Smiley was allowed to remain free because he is helping his mother maintain her real estate business as she undergoes cancer treatment.

Montgomery's request to remain free because of his part-time care for his 2-year-old daughter did not meet the extraordinary circumstances required by the law, Lee said.