It wasn't a film set and there were no cameras rolling, but when the director of the Bourne Identity saw a cargo ship slam into a speedboat on the Hudson River, he jumped into action.
Doug Liman and producer Avram Ludwig were on their sailboat on the river in New York at around 1am on Wednesday when they saw a black cargo ship and a speedboat on a collision course.
They watched in horror as the large craft crashed into the smaller boat and kept going.
Both Liman and Ludwig said they never expected to find any survivors, but found four people screaming for help when they sped to the scene.
They rescued three passengers from the water, while the owner of the vessel, who refused to leave his speedboat, held on to a small piece of hull until police and fire crews arrived.
All four were brought to shore and taken to St Vincent's hospital with minor injuries.
Police said the cargo ship probably did not notice the smaller boat.
The coastguard would not confirm the crash today, saying only that the agency was investigating a "possible collision" between two vessels on the Hudson.
Liman and Ludwig, who were in New York yesterday filming a new movie called Fair Game, said it was "a miracle" all four people survived the crash.
"I just think the Hudson River, at this moment in time, has to have some kind of good karma," said Liman, recalling how Captain Chesley "Sully" Sullenberger landed a US Airways plane safely on the river in January after the aircraft struck a flock of geese.
Liman, who has directed numerous films, including Swinger and Mr And Mrs Smith, said no Hollywood action sequence could compare with the rush of adrenaline he felt during Wednesday's rescue.
But Ludwig said producing action movies had helped the two deal with emergency situations.
"Simulating life-threatening situations prepares you for real life," he said. "We can keep a level head under a lot of pressure."