Director Kathryn Bigelow and screenwriter Mark Boal, the team behind “The Hurt Locker,” plan to shoot a film about the search for Osama bin Laden this year. (Alberto E. Rodriguez/GETTY IMAGES FOR DGA)

Like most Americans, Mark Boal was overwhelmed with emotion Sunday night when he heard that Osama bin Laden had been killed.

It wasn’t until a reporter e-mailed him an hour later that he realized he now had a new third act.

For the past decade, Boal — a former journalist who became a screenwriter and won an Oscar last year for “The Hurt Locker” — has been working on a screenplay about the hunt for bin Laden. He has partnered with “Hurt Locker” director Kathryn Bigelow.

Just as “The Hurt Locker” focused on an elite bomb squad working in Iraq, Boal’s untitled bin Laden script revolves around the special operations personnel and intelligence officials who planned to capture or kill the al-Qaeda leader, and was based on extensive research Boal conducted through his contacts with the U.S. military.

Last weekend, Boal and Bigelow were in what the screenwriter calls “soft pre-production” with the film, scouting locations, meeting with actors and planning on visiting Afghanistan for a research trip. When he heard that bin Laden was dead, “I actually didn’t think about the film at all,” the hard-to-reach Boal said on Tuesday, reluctantly agreeing to a brief phone conversation between meetings. “I was just stunned. It brought back so many memories of 9/11. It was just a really powerful moment.”

He said, “I’ve been following the intelligence efforts to kill or capture bin Laden as best as I have been able to over the years.” He remembers pitching the story to news magazines as far back as 2003, when he was a freelance writer. “So [his death] was certainly an eventuality that I was prepared for, and on some level anticipating, but not the exact timing of it. . . . The bigger picture is there’s now a definitive ending to this particular chapter in American history. That definitely makes my job a little more straightforward.”

Boal now finds himself in the rare position of rewriting his script virtually in real time, as he scours news reports and calls on his own sources to piece together the remarkable events of last weekend.

“What I’m doing is figuring out how to respectfully and truthfully represent the work of all the players in this saga, from the intelligence guys to the policymakers in the White House to the work force on the ground,” he said

Bin Laden most likely won’t appear in the movie. “The focus is going to be on the men and women — and there are some interesting women involved here, too — tasked with hunting the guy,” Boal said.

Last January, Variety reported that Boal and Bigelow’s bin Laden film would be financed by producer Megan Ellison through her company, Annapurna Pictures. More recently, Australian actor Joel Edgerton (“Animal Kingdom”) has been mentioned as a possible cast member. Boal said that plans are still on track to film late this summer or in early fall, with a 2012 release. He declined to specify locations, “for any number of reasons, mostly having to do with wanting to be respectful of the fact that this is a story that’s still inflammatory to a lot of people in the world.”

Although Oliver Stone has been attached to “Jawbreaker,” an adaptation of CIA field commander Gary Berntsen’s memoir of his pursuit of bin Laden, Bigelow and Boal’s project looks to be the front-runner, timing-wise. What’s more, its third act will benefit from current events. “It’s such a resounding tactical victory and moral victory,” he said.

Boal considers it a “privilege” to write about the commandos who executed the mission. “It’s an extraordinary group of people who, by their own professional credo, almost always go unrecognized. And they’re some of the most interesting and committed and complicated people I’ve ever come across, which is probably why I like to write about them.”