Emergency personnel work at the scene, Thursday, April 11, 2019, in Durham, N.C., the day after an explosion and building fire caused by a gas leak killed one person and injured more than two dozen, including nine firefighters. (AP Photo/Gerry Broome)

DURHAM, N.C. (AP) — The coffee shop owner killed in a North Carolina gas line explosion was last seen in the doorway of his business after firefighters evacuated his customers and told him to leave, the fire chief said Thursday, as city officials gave new details about fiber network construction that preceded the blast.

Communications company Crown Castle said a contractor was doing fiber-optic work in the area where police have said a gas line was hit and began leaking shortly before the explosion.

Meanwhile, authorities raised the toll of people injured to 25, including nine firefighters. Police said Kaffeinate coffee shop owner Kong Lee, 61, was the only person killed in the blast that leveled the century-old building and damaged others.

A gas leak had been reported about a half-hour before the blast Wednesday morning, and firefighters were working to get people out of nearby buildings when the explosion occurred. In the hours after the blast, Durham police spokesman Wil Glenn said a contractor boring along a sidewalk hit a gas line and caused the leak, while Deputy City Manager Bo Ferguson said work to install a fiber optic communications network appeared to be involved. It's still not clear what made the gas ignite.

On Thursday, Ferguson said the permit to do the work was held by a subsidiary of Crown Castle, and that Charlotte-based engineering company Utilis was overseeing the construction. Ferguson said it's also possible that another subcontractor was involved in the work.

Crown Castle later issued a statement saying its subsidiary Fibertech Networks had hired a contractor that was installing fiber in the area prior to the explosion. It declined to answer further questions, citing the ongoing investigation.

"We are devastated by this tragic event and its impact on the Durham community," said the statement attributed to Crown Castle area president Cathy Piche. "We grieve the loss of life and our continued prayers go out to the people who were injured and their families."

Two officials with Utilis didn't immediately return messages seeking comment.

Fire Chief Bob Zoldos said Thursday that firefighters told people to evacuate the coffee shop that occupied a storefront in the building and got about 10 customers out, but Lee declined to leave. He was last seen in the doorway as a firefighter went to find a police officer to force him to evacuate.

"All the people in the business did evacuate, other than the owner. The owner decided that he did not want to evacuate," he said at an afternoon news conference, elaborating on earlier comments. "Our engine captain went to find a police officer to enforce that evacuation order, and that's when the building exploded and collapsed."

Zoldos said some of his firefighters continued to work the scene after suffering cuts from flying debris or other injuries from "the concussion of the blast wave."

A man who answered the door at a Raleigh home address for Lee told a reporter Thursday he didn't have anything to say.

Durham Deputy Fire Chief Chris Iannuzzi said at least 15 buildings were damaged by the blast in a downtown shopping district made of converted tobacco warehouses and other industrial buildings. Some windows were shattered blocks away. Zoldos said several buildings have been condemned, and others are being evaluated.

Authorities say no one else was believed to be trapped or unaccounted for, but a search of the rubble was continuing as a precaution. Several dozen firefighters, state agents and other authorities could be seen at the site of the explosion Thursday morning, including one officer leading a search dog in and out of the rubble pile.

The destroyed building also housed offices for Prescient Co., a technology company focused on the building industry. Company officials said their employees were able to safely evacuate shortly before the explosion.

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Associated Press writer Emery P. Dalesio in Raleigh, North Carolina, contributed to this report. Follow Drew at www.twitter.com/JonathanLDrew .

Charred remains are piled in a heap of rubble, Thursday, April 11, 2019, in Durham, N.C., the day after an explosion and building fire caused by a gas leak killed one person and injured more than two dozen, including nine firefighters. (AP Photo/Gerry Broome)
Emergency personnel search through rubble, Thursday, April 11, 2019, in Durham, N.C., the day after an explosion and building fire caused by a gas leak killed one person and injured more than two dozen, including nine firefighters. (AP Photo/Gerry Broome)
Charred remains are piled in a heap of rubble, Thursday, April 11, 2019, in Durham, N.C., the day after an explosion and building fire caused by a gas leak killed one person and injured more than two dozen, including nine firefighters. (AP Photo/Gerry Broome)
Charred remains are piled in a heap of rubble, Thursday, April 11, 2019, in Durham, N.C., the day after an explosion and building fire caused by a gas leak killed one person and injured more than two dozen, including nine firefighters. (AP Photo/Gerry Broome)