(CNN) -- It started with a father sending text messages to his daughter during the previews of a movie.
It ended with the 43-year-old man shot dead amid the theater seats, and a 71-year-old retired police officer in custody.
The shooting Monday during a 1:20 p.m. showing of "Lone Survivor" at a Wesley Chapel, Florida, movie theater escalated from an objection to cell phone use, to a series of arguments, to the sudden and deadly shooting, according to police and witnesses.
As a male moviegoer texted, the man seated behind him objected, and asked the texter to put his phone away.
They argued several times, according to police and witnesses, and the man who was texting watched as the other man walked out of the theater. Curtis Reeves, a retired police officer, apparently went seeking a theater employee to complain about the texting, police said.
Two seats away Charles Cummings and his son watched the squabbling.
When Reeves returned, he was without a manager.
"He came back very irritated," Cummings said.
The man who had been texting, Chad Oulson, got up and turned to Reeves to ask him if he had gone to tell on him for his texting. Oulson reportedly said, in effect: I was just sending a message to my young daughter.
Voices were raised. Popcorn was thrown. And then came something unimaginable -- except maybe in a movie. A gun shot.
Oulson was fatally wounded. His wife was hit, too, through the hand as she raised her hand in front of her husband as the shooter drew a handgun.
Oulson staggered toward the Cummings and fell on them, Charles Cummings said.
The shooter sat down and put the gun in his lap.
It happened that an off-duty deputy sheriff from Sumter County was among the 25 people theater at the Grove 16 complex. He rushed to the scene to make sure no more shots were fired and the shooter would stay put.
It also happened that there were two nurses there and one came to Oulson's side and performed CPR until paramedics arrived.
Oulson later died. His wife, Nicole, suffered a non-life threatening wound to her hand.
"I can't believe people would bring a pistol to a movie," said Cummings, a Vietnam veteran who had celebrated his birthday by going to a movie with his son.
Reeves was sitting with his wife, Pasco County Sheriff Chris Nocco said.
CNN affiliate Bay News 9 reported that Reeves was arrested on a charge of second-degree homicide. It could not be determined Monday night whether he had retained an attorney.
Reeves retired in 1993 as a captain with the police department in nearby Tampa. He was also director of security at Busch Gardens until 2005, the station reported.
Bay News 9 spoke to a neighbor of Oulson's who said the dead man was a very nice guy who he couldn't envision being involved in an incident like this.
"Always smiling. I've never seen him angry," Bill Costas said. If I needed help with something he was always there.
"Totally different guy. Like I said, it just doesn't make sense to me. Not from what I know of him."
The shooting happened at about 1:30 p.m. inside one of the theaters at the Grove 16 complex, sheriff's spokeswoman Melanie Snow said.
"This was an isolated altercation between two guests that escalated unexpectedly. The safety, security and comfort of our guests and team members are always our top priorities, and we are truly heartbroken by this incident," Cobb Theatres, which operates the Grove complex, said in a written statement.
On the theaters' website is a list of prohibited items and actions. Among them: No cell phone use, including texting, in the theater auditorium. And no weapons allowed.
CNN's Suzanne Presto contributed to this report.