Fire marshals have added a fourth suspect to their list of “persons of interest” in the Wednesday night arson fire that engulfed a Fry Street icon.

DRC/Gary Payne

Denton firefighters work Wednesday night to contain a fire that destroyed the former location of The Tomato pizza parlor on Fry Street. The building and several others nearby were scheduled for demolition to make way for a controversial new retail development.

Fire Marshal Rick Jones said Thursday that a fourth person, not necessarily connected to the three who were detained and released Wednesday night, has emerged in the investigation of the fire that destroyed the building recently vacated by The Tomato pizza restaurant.

He would not elaborate, saying it was too early in the investigation to give more details.

Fire investigators worked at the scene most of Thursday, gathering evidence, and then left the rubble to allow bulldozers to begin razing the main block of Fry Street. The block is being torn down to make way for a new retail and restaurant area.

Thursday morning, Jones asked for help from the Bureau of Alcohol, Tobacco, Firearms and Explosives, and an ATF arson team brought a dog to try to detect the presence of an accelerant in the rubble. Jones would not say whether the dog found any accelerant.

“We have confirmed it was arson,” Jones said. “We used the canine as a tool to help us determine the origin of the fire, and once we get the results back from the state arson lab, we’ll be able to determine what evidence we have.”

The fire marshal said it would take a week to 10 days for the lab to finish testing the evidence the officers were carefully placing in a shiny metal bucket Thursday.

Jones said that the condition of the building, which was old and had a lot of exposed wood due to partial demolition, provided good fuel for the flames, which at first soared high into the air and leapt out holes where windows and doors had been.

University of North Texas and Denton police detained three men at the scene but later released them after intensive questioning. Witnesses had pointed them out, saying they were running from the building just before the flames erupted. Jones said there was some evidence they might be involved but not enough to arrest them.

City officials said news of the arson case perplexed and disappointed them.

“I don’t know what good that that would achieve for them to set fire at that facility, because it was already set for demolition,” Denton Mayor Perry McNeill said. “It disappoints me anytime we have that kind of activity — if it is indeed arson — that we have an element that for whatever reason would break the law.”

McNeill said firefighters put their lives at risk anytime they battle a blaze.

“That’s a concern always,” he said.

The fire investigators picked through the sooty pile of bricks Thursday while city workers reconnected power lines burned in the conflagration. A worker directed traffic down Hickory Street past the Fry intersection, shouting and beckoning to drivers who held up traffic to gape at the mess and snap photos on their cellphones.

The scene was even more chaotic at the height of firefighting efforts late Wednesday and early Thursday, as hundreds of young people milled behind yellow crime scene tape in the rain watching.

Police saw flames shooting from the roof amid a heavy smoke cloud about 11 p.m. and called for the fire department. Battalion Chief Cort Higgins said the building was fully in flames when firefighters arrived.

“The building was going down anyway,” Higgins said. “But we were worried about extension to some of the adjoining buildings that are going to remain, and we had power lines down and burning.”

There also was danger of sparks from the high flames jumping the street and spreading the damage across Fry to the buildings there, he said.

Power lines fell on a car parked in front of the building, and the resulting fire destroyed it.

An announcement last year that United Equities Inc. had bought most of the city block that contained such college hangouts as The Tomato and Mr. Chopsticks caused an uproar that continued this week as preparation began to bulldoze a strip of buildings.

United Equities plans to build a modern business and restaurant center there, but representatives have promised it will retain some of the spirit of the old buildings.

Concerned residents formed a group called Save Fry Street to try to preserve the 1920s-era buildings but failed to stop the demolition.

Higgins said the shell of the building that remained was unstable and too dangerous to leave standing. In the early morning hours, a bulldozer knocked down the two outer walls facing Fry and Hickory streets.

Save Fry Street issued a statement late Thursday condemning the arson fire.

“Last night’s activities were not only of obvious disservice to United Equities, but contaminate the earnest, year-long efforts of S.F.S. and the Denton community majority that have desired a different result for the structures,” the statement reads. “Save Fry Street also regrets that United Equities didn’t better secure the buildings from becoming such an attractive nuisance during their final hours.”

Bernadette Wise, a property manager with United Equities, said in an e-mail Thursday that the company needs to move forward with the project.

“We are very thankful that no one was hurt, and we are working in conjunction with the fire department to conclude their investigation so we may proceed with the cleanup process as soon as possible,” she wrote.

Emergency personnel battled the fire while excited bystanders watched from a safe distance marked out with yellow tape and enforced by police. They emerged from nearby bars, and a party atmosphere hung in the air with the heavy smoke.

Many watchers said they and people around them were receiving phone calls and text messages about the fire within minutes of the flames starting to show.

By 12:30 a.m., an amateur video was already posted on YouTube.com.

Many bystanders said that with all the controversy surrounding the Fry Street redevelopment, they were not surprised by the arson.

UNT junior Al-Dana Aldana said the fire might have been a little anticlimactic considering the buildings were going to be demolished anyway, but it was a way to send the historic buildings off with a bang.

“The most they accomplished was getting people’s attention one last time before Fry Street is gone,” he said.

Organizers of Save Fry Street said there wasn’t enough protection around The Tomato in the first place.

“It hasn’t been a barrier at all,” said Chris Flemmons, an organizer of the group. “Police have told kids to get out of there.”

“You knew someone was going to get hurt or something,” said Martin Iles, another supporter of historic preservation. “It was coming to a head.”

Both Flemmons and Iles said the arson was a disservice to everyone involved.

“It’s just more negative chaos associated with a corner which has already received negative attention,” Iles said.

UNT sophomore Abbey Muzzy said the fire wasn’t the smartest way to protest, but it was someone’s way of sending a message.

“Everyone’s so pissed about everything being torn down,” she said. “It’s poetic.”

Texas Woman’s University senior Brandy Gilbeaux, who has lived in Denton her entire life, said it’s always sad to see something historic go, but she’s interested to see if what developers put in its place will be worth what was taken down.

Gilbeaux said she felt the fire was not set with malicious intent but by people who wanted to show that The Tomato was symbolic to the community.

“It made a statement for what it was,” she said. “It showed that it meant something to the people here.”

Staff writer Lowell Brown contributed to this report.

DONNA FIELDER can be reached at 940-566-6885. Her e-mail address is dfielder@dentonrc.com.

SARAH CHACKO can be reached at 940-566-6876. Her e-mail address is schacko@dentonrc.com