The Uber driver arrested for the deadly Kalamazoo, Michigan, killing spree was charged Monday with six counts of murder and ordered held without bail.
Prosecuting attorney Jeff Getting said Jason Brian Dalton "admitted his involvement" in the killings and was found with what appears to be the murder weapon. But the 45-year-old suspect kept quiet during his brief hearing.
"I would prefer just to remain silent," Dalton responded when the judge asked if he had anything to say.
Appearing on a live feed from the Kalamazoo County Jail, Dalton wore glasses and an orange prison uniform. He sat quietly as the judge read the 18 count against him, which also included two attempted murder and eight felony firearms charges. He is due back in court on March 3.
Getting said they still don't have a motive for the mayhem.
"The police are continuing to investigate as to why this happened," said Getting, who had previously described the killings "as intentional, as deliberate, as cold."
"This was not a momentary lapse," he said. "There was nothing that provoked this. There is videotape of these incidences. He walked up to people and he shot them."
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In a statement, Dalton's family expressed sympathy for the victims but gave no new insight into the tragedy.
"We are deeply sorry and praying for everyone affected," their statement read.
An insurance adjuster who was moonlighting as an Uber driver, Dalton cruised around the city Saturday night picking his targets seemingly at random.
When it was over, six people were dead and two more wounded, including a 14-year-old girl who remains in critical condition. Then Dalton apparently continued to pick up fares before finally being caught.
A married father of two, Dalton had no police record or anything in his background "that would lead us to believe he was capable of this type of behavior," Kalamazoo Police Chief Jeff Hadley said on Sunday.
Also, the federal Bureau of Alcohol, Tobacco, Firearms and Explosives said Dalton was not barred from owning the "many long guns and handguns" that police removed from his home, The Associated Press reported Monday.
Meanwhile, heartbroken Kalamazoo residents gathered Monday at St. Augustine Cathedral for a Mass in memory of the victims: Richard Smith, 53, his 17-year-old son, Tyler, both of Kalamazoo; 60-year-old Mary Jo Nye of Battle Creek; her 62-year-old sister-in-law Mary Lou Nye of Baroda; 68-year-old Barbara Hawthorne and 74-year-old Dorothy Brown, both of Battle Creek.
Earlier, President Obama said he he called "the mayor, the sheriff, and the police chief there and told them that they would have whatever federal support they needed in their investigation."
"The attack in San Bernardino killed 14 of our fellow Americans," Obama said in remarks to the National Governor's Association. "And here's a hard truth: We probably lost even more Americans than that to guns this weekend alone. On Saturday, another one of our communities was terrorized by gun violence."
Michigan Governor Rick Snyder ordered flags across the state lowered to half-staff for six days starting Monday — one day for each of the victims.
"I met with two (victim) families in Kalamazoo yesterday," Snyder said during a press conference. "What a tough situation."
This article originally appeared on NBCNews.com.