It's too early to call it unstoppable -- or even a definite movie -- but Fox has opened a production office here and is scouting locations for a big-budget action film.

Called "Unstoppable," it could be directed by Tony Scott and star Denzel Washington and Chris Pine, although a source close to the production said the movie has not been green-lit (or given the go-ahead) and that the trio is not yet signed.

If all of that happens, "Unstoppable" would be the fifth collaboration between director Scott and Washington, after "The Taking of Pelham 1 2 3," "Deja Vu," "Man on Fire" and "Crimson Tide." Pine, meanwhile, is one of the summer's breakout stars, thanks to his turn as James T. Kirk in "Star Trek."

The movie is about a train with toxic chemicals speeding out of control. Scott isn't known for small, intimate pictures and two-time Oscar winner Washington is an automatic attraction.

When Washington visited the Wilkinsburg Boys & Girls Club in October 1994, he charmed children and adults by flashing that dazzling smile, signing autographs, posing for photos and asking thoughtful questions of the breathless strangers he met.

If "Unstoppable" lives up to its name, it likely would shoot in the fall and there is no way of knowing how much would be filmed in the Pittsburgh area. "Warrior," wrapping up production this month, would be finished, allowing the city to keep up its remarkable streak of production.

Dawn Keezer, director of the Pittsburgh Film Office, said yesterday, "We've been working with 'Unstoppable' for quite some time and we're very hopeful."