The decision came after the jury told the judge it was "hopelessly deadlocked" about seven-and-a-half hours into the second day of deliberations.
The jury went home Saturday after about seven hours and some questions for the judge on procedure.
There were 16 seated jurors in the trial. Twelve were selected at random to deliberate.
Defense attorney Jim Logan says, "Leon Houston still insists that he's not guilty of any of the charges that are placed against him."
Logan also said he understood the jury's dilemma. "They spent a great deal of time analyzing all the evidence and the appropriate things to do so...it is a difficult case."
Leon showed little emotion Sunday when the mistrial was declared.
His sister, Lisa Burris, said, "We just hope that both families, all families involved, through this process recognize that everybody's affected by it. It's not just the victims. It's not just the defendants. Everybody's affected. It was a bad thing that happened."
The families of the victims and prosecutor Gus Radford declined to speak to the media after the mistrial was declared. Family members left with escorts by officers.
Leon and his brother, Rocky Houston, are both charged in the shootout that happened at Leon's home.
Leon is charged with two counts of first degree murder and one count of felony murder.
Both sides are scheduled to meet with the judge on August 20 for a status hearing on the case.
Rocky's trial was scheduled for November, but Leon's re-trial may take place instead, according to his attorney. The brothers might also be tried together or Leon might still be tried separately next year.
For complete coverage of the Leon Houston trial, click here.