Two people were hospitalized in Fort Belknap after rolling their car just west of Dodson on Highway 2 early Wednesday morning.
Montana Highway Patrol trooper Matt Finley, who investigated the 12:40 a.m. accident, caught up with the couple in the hospital.
"The driver told me she had swerved to miss a kangaroo," he said. "I laughed, and the nurses laughed, and I didn't really believe her."
But he drove back to the crash site and sure enough, there was a kangaroo standing in the ditch about 40 yards away, the trooper said.
Nearby residents told him there is a kangaroo farm west of Dodson. He also learned that kangaroos are prone to escape enclosures.
"Not because they jump the fences," he said. "Apparently they like to go under or through them."
It's possible the escapee wasn't a kangaroo, but a wallaby. Kangaroos are illegal to own in Montana, but wallabies are not, said Mike Lee with Montana Fish, Wildlife and Parks.
Although close cousins, wallabies are generally smaller than kangaroos with slightly different teeth and shorter legs. And wallabies prefer leaves while kangaroos favor grass.
Finley acknowledged he's gotten plenty of questions about the wreck. Mostly, people aren't even sure what to ask him.
"It's not really something I was expecting," he said about the cause of the accident.
He says the people in the vehicle suffered minor injuries after their vehicle rolled.
He says he did not try to capture the recalcitrant macropod.
Dodson is located in Phillips County in rural northern Montana.
The Associated Press contributed to this story.