The music playing inside a truck in a convenience store parking lot was too loud Saturday night, so an Alabama sheriff asked the driver to turn down the volume.

That’s when the 18-year-old driver pointed a gun at the sheriff and shot him in the head, killing him, authorities say.

That account was among the shocking details emerging Sunday following Saturday’s fatal shooting of Lowndes County Sheriff John Williams Sr., a no-nonsense law enforcement professional and former Marine, known as “Big John.”

ALABAMA SHERIFF SHOT, KILLED AT CONVENIENCE STORE; SUSPECT SURRENDERS AFTER 4-HOUR MANHUNT: REPORTS

The suspect in the killing is the son of a sheriff’s deputy from Montgomery County, according to WSFA-TV.

Charles Benson, a customer at the QV store in Hayneville, outside Montgomery, where the shooting occurred, told the Montgomery Advertiser he saw everything.

“Right there at Pump 8,” Benson said, pointing to the crime scene. “Big John comes up and asks the young man about the loud music, just like he has done hundreds of times before. Big John don’t take no foolishness.

“That's when he got shot. I don't understand it. The sheriff is gone over loud music? It just don't seem right.”

"I don't understand it. The sheriff is gone over loud music? It just don't seem right." — Charles Benson, witness to fatal shooting

The shooting happened around 8:15 p.m. The suspect, identified as William Chase Johnson, initially fled but returned to the crime scene with a firearm about four hours later and was taken into custody, according to reports.

Johnson is scheduled to appear Monday morning in Lowndes County District Court to face murder charges, AL.com reported.

The Montgomery County Sheriff’s Office confirmed that Johnson is the son of one of its deputies, according to WSFA.

Officials from the Alabama Law Enforcement Agency wouldn’t comment when the Advertiser asked if Williams was on duty and in uniform at the time of the shooting, or whether he was using his patrol car or an unmarked vehicle. The case remains under investigation.

Initial reports that Williams had been responding to a call from the store were not accurate, according to local media.

On Sunday, a crowd of people from around Lowndes County gathered in Hayneville to pay tribute to Williams, who was first elected sheriff in 2010 and had held the job ever since.

“Big John was one that loved everybody,” Alicia Davis, a minister at Greater Mount Zion AME Church in Hayneville, told AL.com. “When he saw you, he spoke to you. It doesn’t matter what color with him. He loved everybody. He cared for everybody. Young people, he would come pull them aside, talk to them. And he saved a lot of people.”

"Big John was one that loved everybody. When he saw you, he spoke to you. It doesn’t matter what color with him. He loved everybody. He cared for everybody." — Alicia Davis, minister, Greater Mount Zion AME Church, Hayneville, Ala.

A local politician, state Rep. Kelvin Lawrence, said Williams’ devotion to the community extended beyond law enforcement.

"He led the procession in every funeral,” Lawrence told AL.com. “If it was a family reunion, he was there. So, he just did a lot of stuff in the community to make people feel safe and appreciate the law enforcement here in Lowndes County. He just did a lot of things that you wouldn’t see the average sheriff would do in terms of being visible in the community.

Judge Adrian Johnson spoke of Williams’ charitable spirit.

“If he found out somebody didn’t have a Christmas present for their child, he’d go out of his own pocket and go buy that,” Judge Johnson told the news outlet.

Alabama Gov. Kay Ivey was among the first public officials to pay tribute to Williams after his death Saturday, calling him “a consummate professional and pillar of his community.”

On Sunday, more tributes arrived, especially from law enforcement officials from around the country.

“Sheriff Williams led a life of significance – a life that mattered,” wrote Bill Bratton, who led police departments in Boston, New York and Los Angeles. “He served his community for 40 years. We will #NeverForget. My prayers are with his family.”

Alabama Sens. Richard Shelby and Doug Jones also paid their respects.

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“His service to the people of Lowndes County and the state of Alabama will never be forgotten,” Shelby wrote.

Williams’ death was “a sad and tragic loss for his community, his state and law enforcement everywhere,” Jones wrote. “He was a friend and consummate public servant who devoted his life to public safety.”

By law, Lowndes County Coroner Terrell Means becomes acting sheriff in the county until Gov. Ivey appoints a new sheriff, WSFA reported.