To the Warrens, their presence was one more thing they could do to support their neighbors, the Johnsons, since their son was killed during a routine Sunday morning patrol.
To many others, who came from all around the state and elsewhere, Thursday was a chance to pay respect to an officer whose loss reverberated far beyond the community he served.
"It's overwhelming," Karen Warren said as she looked over the crowd and as tears welled in her eyes.
"It's a great tribute not just to Derek but to the police force to know that everybody cares," Lee Warren said.
Police say Johnson was shot by a transient after the 32-year-old officer pulled up in his patrol car to investigate the man's vehicle. The suspect, Timothy Troy Walker, then shot his passenger, Traci Vaillancourt, and himself, but police say the two are expected to survive.
Inside the arena, a line of pictures and mementos from Johnson's life led to a row of bouquets at the front of the large room. Johnson's casket, which according to police officials was open during the viewing, sat in the center. At the end of the day, the casket was closed and covered by a black curtain. Two video screens played slide shows of Johnson, almost always with a smile on his face. A bagpipe recording of "Amazing Grace" played in the background.
Mary and Steve Bartlett, also from Draper, knew Johnson when he was a teenager growing up in their LDS ward.
"He was a great kid even then," Mary Bartlett said.
As they prepared to enter the crowded viewing room, it was hard for them to take in.
"Shock," is how Steve Bartlett described it. "It's hard to believe that this is something that could happen."
Still, it was comforting to see the amount of people who came to pay their respects, he said.
"It's absolutely amazing the amount of friendship," he said. "Just absolutely amazing."
Draper Police Chief Bryan Roberts echoed those sentiments.
"There's been such an outpouring from the community," Roberts said.
The past few days have been tough on the Draper force, a small tight-knit department that counts about 50 employees, he said.
"This reminds you of the risks we have in public safety," and they're risks officers take on willingly, Roberts added.
The most visible contingent at Thursday's viewing was Utah's law enforcement and public safety community. A giant U.S. flag supported by two ladder trucks from Unified Fire Authority and West Valley Fire draped over the stadium entrance. Inside, uniformed officers dotted the crowded line into the arena.
"It affects all of us, said Utah Highway Patrol Sgt. Brett Christensen.
Christensen, who wore his uniform, drove from his home in Utah County with his wife.
"We all know that at any given day it could have been any of us just as easily as it was Sergeant Johnson."