City and county officials expected a good turnout for the widely publicized gun buyback event Saturday morning at Wheeler Avenue — touted as a method of reducing violent crime. But the enthusiastic response still came as a surprise to organizers, which included Harris County Commissioner Rodney Ellis, Mayor Sylvester Turner and Police Chief Troy Finner.

“Even I didn’t think it was going to be this many people the first time,” Finner said during a news conference at the church. “We’re going to get a chance to serve them and we’re going to work out a process today.”

Saturday’s event — the first gun buyback held by the city since 2009 — came amid growing scrutiny over the prevalence of firearms in the United States. Gun violence has become the leading cause of traumatic death among children, and the city and county have funded various programs to address the problem.

The buyback stemmed from one of those programs, One Safe Houston, which leverages about $53 million in federal relief funds to reduce violent crime.

While public officials characterized Saturday’s event as a clear success, it’s an open question whether buyback programs accomplish the intended goal. Criminologists say they often offer little incentive for people with intent to use a gun to turn over their firearm and more often yield old guns that someone may no longer want in their home.

But Finner says that preventing even one violent crime makes the program worth it. Based on Saturday’s response, he hopes to continue offering buyback programs with more staffing to handle the capacity.

The event operated on a voluntary, no-questions-asked basis. Cars snaked through the Wheeler Avenue parking lot, where, one-by-one, Houston Police Department field training officers collected the weapons, ensured they were not loaded and fastened orange zip ties to the action — the part of the gun that loads, fires and ejects a cartridge.

Evidence technicians then input the serial numbers into a database to check whether they were stolen or used in a crime. The identification process will be completed after the event. If stolen, police plan to return it to the owner. If the gun was used in a crime, police will file it away into evidence.

All other weapons will be broken into pieces, then incinerated, police officials said.

Harris County District Attorney Kim Ogg criticized the event’s parameters in a letter dated July 28 to Finner, Sheriff Ed Gonzalez and Harris County Precinct 2 Constable May Walker.

The letter, obtained by the Houston Chronicle, said the event could “harm public safety, impede the prosecution of violent criminals and encourage the theft of firearms in and around Harris County.” The “no-questions-asked” policy amounts to anonymity and immunity for anyone who turns in a weapon, some of whom could be considered witnesses to a crime, Ogg wrote.

“Neither anonymity nor immunity is within the statutory authority of a law enforcement agency to extend to witnesses,” Ogg wrote.

The letter went on to say that the gift cards further complicate the situation, because money given to a witness needs to be disclosed to the defense in a criminal case. She said the program could make law enforcement a party to tampering with evidence and may cause “irreparable harm” to the prosecution. She urged law enforcement to carefully document evidence to prevent “weapon laundering” charges.

Turner and Ellis both said they were not aware of the letter until Friday afternoon.

“HPD was very meticulous in the gun buyback program,” Turner said. “That’s one of the reasons why the lines didn’t move as quickly. ... If she had concerns, she should have voiced them a lot sooner.”

Ellis also issued a statement, saying, in part, that the letter was “at best uninformed and cynical, and at worst a political stunt to minimize the hard work of police and public officials to proactively stop gun violence.”

The reasons for participation varied widely.

Cynthia Bowie, of South Park, had forgotten that a family member left her a small, .22-caliber revolver. She found it in a box at home and has been looking for a way to get rid of it ever since.

“You need to protect yourself these days,” she said. “But I just don’t like guns.”

Fifth Ward resident Annie Taylor doesn’t remember how she came into possession of three pistols about 40 years ago. She’s concerned about someone breaking into her home and stealing them.

“I wish they would do this program every six months to get more weapons off the street,” she said. “Too many teenagers are getting their hands on these guns.”

For Mark Hein, the decision was purely economic.

He drove from Northside for the event with his young grandson to make a few bucks off weapons that he considered unusable, including two shotguns and a hunting rifle.

“Something that’s probably worth $2, you can get $50 for it,” he said, adding that he owns about two dozen other firearms, mostly for hunting.

Drivers complained of the sluggish line, with some waiting up to 30 minutes without moving. Houston police stayed long after the event was scheduled to end to serve as many people as possible.

In addition to the long wait, the massive turnout gave way to another problem: Police said they were aware of one person inquiring to waiting drivers about buying their firearms.

“He has a right to do that as long as it’s legal,” Finner said. “We’re going to focus on what we have going on here at the moment. There’s always going to be outliers.”

Jen Rice contributed to this report.

julian.gill@chron.com