Revere and two companions were riding toward Concord to continue to warn the people when they were met by a roadblock comprised of ten British regulars. His companions outran the roadblock, but Revere was taken prisoner. During his interrogation by British officers, he embarrassed them by telling them even more than they themselves knew about their own mission. He also informed them that he had been riding around warning everyone in the vicinity of the British plans, and that, if they remained in the area much longer, there would soon be hundreds of men massing, and their lives would be in jeopardy.
A few shots began to ring out in the vicinity of Lexington's meeting house, making the British regulars very uneasy....at which point they released Revere (and other captives) so as to be able to retreat as quickly as possible.
Revere's story about the soon-to-be-massing hundreds of men was a bluff.