The events of Sept. 11, 2001, are days away from reaching the five-year mark, and Hollywood has decided to commemorate the date with two films: Paul Greengrass' United 93 and Oliver Stone's World Trade Center. Much has been made of the notion that these two films might be coming out too soon, and that it might be painful for some to relive that shocking, blue-skied day.

While no one has ever lost money underestimating Hollywood's taste, it must be said that there are many precedents of Hollywood studios responding immediately to national emergencies, from silent films of World War I trench warfare to the battle on American streets during Vietnam. If anything, Hollywood has behaved rather circumspectly in waiting five years to explore 9/11, while American theater (The Mercy Seat, Omnium Gatherum, Recent Tragic Events and The Guys, which became an independent film) responded more quickly.

Of the two films, United 93 is by far the most powerful (World Trade Center will be reviewed in two weeks). It is a real-time reenactment (and, in some cases, re-imagining) of what occurred on the fourth fatal flight of that day. While the first two hijacked planes tragically met their destined targets, and the third might have possibly hit its assignment, the fourth, United 93, crashed in rural Pennsylvania, after what seems very likely to have been a counterattack against the hijackers by the passengers.

Whereas Stone's effort is a propagandistic film-as-cudgel complete with all of Hollywood's beloved, feel-good clichés, United 93 plays like a raw documentary. Greengrass made some astonishing decisions in this film. First, many of the public officials and air-traffic controllers who worked through those horrifying few hours appear in United 93 as themselves, re-creating (one hopes for them cathartically) their own actions in their own words.

Second, the passengers on the plane are primarily played by good supporting actors who have appeared in thousands of primetime TV shows, soap operas and commercials, but who are not immediately recognizable faces or household names. By this choice, Greengrass assures that we view the people on the plane, and those on the ground trying to save it, as wholly ordinary. These people could be any one of us. Indeed, few names are uttered on the plane. It is from their biographies from the weeks after the events that you recognize Mark Bingham (Cheyenne Jackson), Thomas E. Burnett, Jr. (Christian Clemenson) and flight attendants Sandra Bradshaw (Trish Gates) and Cee Cee Lyles (Opal Alladin).

Even knowing the plane's fate, United 93 is intensely suspenseful. The film opens in the hotel rooms of the hijackers as they prepare for their journeys to the planes with prayers. At the airports, passengers are checking in for their various flights, while behind the scenes officials are preparing for a relatively easy day — the entire country was bathed in that blue sky.

The first sign that something is amiss comes when air-traffic controllers (as heroic as the firemen and police on the ground) notice a plane on their radar going off course. Surprise quickly gives way to controlled panic, as the controllers and FAA officials try to figure out what's happening. As the first jet smashes into the World Trade Center, the passengers now onboard United 93 are settling in for their flight.

The chaos on the ground (ably fought against by FAA Chief Ben Sliney, playing himself) is nothing compared to the terror soon unleashed on the passengers of United 93. Through the transcriptions of tower-to-cockpit transmissions and private cell-phone messages, Greengrass offers a good speculation on what happened on board the plane. There is no bravado among the passengers. They are frightened for their lives. They know what's happened in New York City and Washington, D.C., and they see no other way out than to desperately try to take over the plane from their captors. The end, the horrible end, leaves us breathless in total darkness.