DENVER — Authorities are defending their attempts to warn residents about a Colorado wildfire blamed for killing three people.

About an hour before the first wave of automated evacuation warning calls on March 26, a volunteer firefighter went house-to-house telling residents to leave. He wasn’t able to reach one woman believed killed in the fire because of a chain across her driveway and her family is questioning why he didn’t walk down to warn her.

Inter-Canyon Fire/Rescue chief Dave MacBean told KMGH-TV that it wasn’t safe because there were trees on both sides of Ann Appel’s narrow driveway, which can help a fire spread. Fire spokesman Dan Hatlestad wouldn’t directly address the family’s question on Tuesday, but the department has said the house wasn’t visible from the end of the driveway.

An aerial map shows the home was about 400 feet from the end of the road, down a curved driveway.

Steep, downhill gravel driveways are common in the rugged area, which is dotted with pine trees.

“Was three minutes too much to warn a resident who had reported the smoke two hours earlier that it was now time to evacuate?” the family said in a statement emailed to The Associated Press by Appel’s sister-in-law, Susan Appel Sorenson.

Appel’s family said the chain across the driveway had been put in place at the suggestion of the sheriff’s department after a burglary years earlier.

“The family understood that fire departments were equipped to open these security devices in the event of an emergency,” the statement said.  

Hatlestad, an information officer who is also a firefighter and paramedic, says firefighters consider vegetation, driveway widths and steep slopes when deciding how to approach a home in danger. They must also equally consider whether they can get themselves and their vehicles out safely.

“The amount of time to approach and evaluate each structure” is also important since firefighters are often rushing for time to notify as many people as possible.

It wasn’t immediately clear what time the firefighter encountered Appel’s driveway, but other firefighters returned there at about 8 p.m. and found the house destroyed and nearby trees on fire, Hatlestad said. Firefighters made a “rapid search” of the area and then responded to other calls, he said.

In a statement, Inter-Canyon said the firefighter began to warn residents to leave at around 4 p.m. with his vehicle lights and siren on. He wasn’t able to reach two other homes because their driveways were blocked.

One of the people he told to leave was Sam Lucas, who was later found dead along with his wife, at their burned-out home.

Lucas was loading things into a vehicle, Hatlestad said, apparently in anticipation of an evacuation.

When the firefighter told Lucas “It’s time to go,” Lucas said something about his home’s fire suppression system, although the firefighter didn’t remember Lucas’ exact words, Hatlestad said.

“Right now you need to get out of here,” the firefighter recalled telling Lucas.

The Jefferson County documents show Lucas had called 911 shortly after 2 p.m. — roughly two hours before his conversation with the firefighter — to report smoke and was told it was a prescribed burn.

Lucas was 77, and his wife, Linda, was 76.

The March 26 wildfire scorched 6 square miles and damaged or destroyed more than two dozen homes in the mountains southwest of Denver.

The timing of the evacuation notices has raised questions about how authorities and residents responded, particularly in the first hours of the fire. Worried residents who called 911 to report smoke were initially told by dispatchers that it came from a prescribed burn that was conducted four days earlier.

Appel was among the early callers, according to audio recordings and documents released by the Jefferson County Sheriff’s Department. She was told crews were on the way.

Later, when the dispatchers realized a wildfire was racing through the heavily timbered area, they told callers to leave.

Jefferson County authorities began sending evacuation notices by automated phone calls shortly after 5 p.m., but the first wave went to the wrong list of numbers. A second, corrected wave of automated calls began at about 5:23 p.m.