COLD SPRING, MINN. - The body of police officer Tom Decker returned home Friday evening in a white hearse, escorted by two dozen wailing squad cars and five fire trucks, just as dusk fell on this central Minnesota granite quarry town.

The 31-year-old officer was shot and killed behind Winners Sports Bar on Main Street the night before, just miles north of the dairy farm where he grew up. The ambush happened when the father of four responded to a report of a suicidal person. Police arrested a community college machine-tool student who lived above the bar in the crime.

Ryan Michael Larson, 34, is being held in Stearns County jail on suspicion of murdering a police officer. Larson was known to carry a handgun, though there had been only hints of violence in his past. Several guns have been located that belonged to Larson, authorities said.

It's the second time in a decade that violence has jarred this town of 4,000. A 2003 shooting left two students dead at Rocori High School, Decker's alma mater.

"With the school shooting not that many years ago, and now this, it's hard on a small town," said Kurt Kubasch as he loaded groceries in his car outside Teal's supermarket.

Late Friday, the slain officer's mother, Rosella Decker, was still busy receiving visits from reporters and grief-stricken relatives and friends at the family's 200-acre dairy farm, where she and her husband, John, raised their eight children.

"We just want people to know how good Tom was," she said, smiling through tears. "He was such a good husband and so good with his kids -- even-tempered, cool."

The farm, with its white clapboard house and barn, is where Tom Decker grew up and still stopped to visit, lend a hand with work or have a piece of his mom's meatloaf, one of his favorite foods.

While the town grieved the loss of a popular young officer, some details began to emerge about Larson. In 2009, court documents show, an ex-girlfriend requested a protective order after "he got very angry and aggressive and agitated," charging and spitting at her and bruising her arm. He paid a $383 fine for disorderly conduct in that misdemeanor case.

Jeff Scoles, who with his parents owns Winners bar, said Friday night that Larson had a permit to carry a handgun and regularly carried a Smith & Wesson .40-caliber semi-automatic pistol. Larson rented an apartment above the bar and acted as fill-in bartender while going to school to be a machinist.

"He liked guns, but he's very cautious with them," said Scoles, who added that Larson also owned an AR-15 assault-style rifle. "He's not the type of person who would go out there like a monster."

A spokeswoman for St. Cloud Technical and Community College confirmed that Larson was studying machine-tool technology. He's lived at various addresses in the St. Cloud area in recent years.

Decker and his partner were responding to a call about a suicidal person in a Main Street apartment when Larson allegedly shot the officer about 11 p.m. Thursday. Decker died at the scene; witnesses said he had been shot in the face.

Scoles, who had spent most of the day with Larson at the family's other Winners bar in Sartell, while Scoles worked and Larson did schoolwork on a computer, said he was shocked to hear Larson had been arrested in the killing.

"He was normal," Scoles said. "In fact, I thought he seemed like he was in a good mood."

Scoles, who grew up in the same town as Larson -- St. Joseph -- and considered him a friend, said Larson and a girlfriend went through a difficult break-up about a year ago, but that Larson no longer seemed troubled by that.

"I don't see him as a murderer," Scoles said. "I'm hoping they find out he didn't do it."

Rosella Decker said she feared the worst late Thursday when she saw Chief Phil Jones and another officer walking up to her door with grim faces.

"I was so hoping he was only hurt," she said.

Dean Demarais, whose son was a high school classmate and wrestling teammate of Decker's, remembered Decker as a happy-go-lucky farm kid. Demarais was playing cards with friends in Winners bar when police rushed in Thursday night.

"They said 'You have to leave right now,'" he recalled. "'And when you leave, put your hands in the air and walk out single file.'"

Demarais said that once outside, they walked past Decker's body on the ground.

Demarais said the shooting, which he didn't hear over the noise of the bar, dredged up bad memories of the Rocori High School shooting, which his daughter witnessed.

"I didn't sleep last night," Demarais said. "It's going to be a long day."

Added retired engineer Joe Peters: "I've lived here all my life, and this is a tragedy that never should have taken place in our town."

Decker's body was brought to Wenner Funeral Home late Friday, and "an officer will be posted at the casket 24/7 until the funeral," said Jones, the police chief.

Decker died "protecting his fellow citizens," Gov. Mark Dayton said in a statement. "For his heroism, we will be forever grateful."