The 28-year-old Iraq war veteran recalled Friday how he then saw black smoke billowing from the glass building and rushed to the scene. There, where the plane had exploded into flames in a suicide attack fueled by anti-government hatred, De Haven found five people trapped on the second floor of the burning office housing Internal Revenue Service employees.
"I wanted to go help," said De Haven, who works for a glass company. "I thought, 'I'm going to go ahead and do it.' I thought my boss would understand."
He quickly hurled his 17-foot ladder onto the building, climbed up and went inside to help the workers escape.
Authorities have credited stories of heroism like De Haven's for keeping the death toll so low in Thursday's crash. The pilot, Andrew Joseph Stack III, and one other person were killed when the software engineer fueled with rage against the IRS slammed his plane Thursday morning into the hulking Echelon 1 building.
"When you look at the building, it's hard to say we were lucky, but we were," said Ernie Rodriguez of the Austin/Travis County EMS. He credited the actions of "many heroic" people who were at the scene.
Stack, 53, apparently targeted the lower floors of the office building, where nearly 200 IRS employees worked. Thirteen people were injured and one remained hospitalized at an Army burn unit in San Antonio.
Authorities have not identified the other person killed. But in a message to employees Friday, IRS Commissioner Doug Shulman said the agency believes an IRS worker was killed, though he cautioned it hadn't been officially confirmed.
"It has left many of them and their families anguished and traumatized and seeking answers as to why anyone would commit such a wanton act of violence and why anyone would take such cruel action against innocent men and women," Shulman said.
In a ranting manifesto posted on a Web site, Stack lashed out at the government - especially its tax code - claiming they robbed him of his savings and derailed his career. In the note, Stack says he realizes "violence not only is the answer, it is the only answer."
U.S. law enforcement officials were trying to determine if Stack put anything in the plane to worsen the damage. One law enforcement official also said they were looking into whether a marital dispute precipitated the attack. All officials spoke on condition of anonymity because the investigation was ongoing.
Six miles away from the charred office building Friday, arson crews inspected Stack's home - which he apparently set on fire before taking off Thursday from an airport 30 miles north.
Across the street, a representative for his wife, Sheryl Stack, told reporters that she thanked her friends and family for their kindness.
"Words cannot adequately express my sorrow or the sympathy I feel for everyone affected by this unimaginable tragedy," the statement read, adding there would be no further comment.
The grandmother of Sheryl Stack's adolescent daughter said the family "had nothing" after the fire.
"I was with her all day yesterday. How would you expect she is doing? She's totally distraught," Jacquelyn "Jackie" Mann said as she was rushing out the door Friday to bring the family clothes.
In a suburb of Los Angeles, the husband of Joseph Stack's ex-wife said she also was distraught and unwilling to answer questions. Wiggs Mendoza said Ginger Stack only occasionally mentioned her former husband - who she divorced in 1999 after 18 years of marriage - but said he was a kind man who had deep affection for the children of her daughter from another marriage.
In the Austin area, the IRS made counselors available to workers and extra security measures were being implemented, said Colleen M. Kelley, the head of the National Treasury Employees Union. She warned that federal tax employees and law enforcement officers were at an increased risk of being targeted by irate citizens.
"It can be dangerous for federal workers to try to carry out their missions; still, they do because they know the public depends on them for vital services," she said in a statement.
A glass workers union said Friday it wants to honor De Haven, the Army veteran, in Washington, D.C., while the company he works for said it has been flooded with phone calls and e-mails calling him a hero.
De Haven said after he extended his ladder and climbed to the second floor, he realized his ladder was unsteady and he couldn't help people down. So, he said he climbed inside the building and helped find a better escape route. Once inside, he found four men and a woman trapped. De Haven said he and another man broke open a window with an iron rod and made their way to a lower ledge where the ladder would be more secure.
"I don't feel like a hero," he said. "I was just trying to help."
More coverage of the Austin IRS attack:
- Stack's Wife Issues Statement; Victim Identified
- Friends, Family Unaware of Stack's Anger
- Manifesto Attributed to Austin's Joseph Stack