The man in the Mercedes SUV told police the brother’s carjacked him less than an hour after they had killed an MIT security officer.
He told police one of the brothers jumped out of their car and opened his door before pointing a pistol at him.
One of the Tsarnaev brothers then made the man drive as was being followed by the other in the Honda they later dumped.
The owner of the SUV escaped when the brothers stopped for snacks.
The Wall Street Journal obtained a copy of the police report in which the man confirmed the brothers "declared to [the victim] that they were the Boston Marathon bombers and would not kill him because he wasn't American."