LONDON — The police in London on Wednesday identified a Sudanese-born Briton from Birmingham as the driver who had plowed a car into three people and crashed outside Parliament, leaving the authorities trying to pry a motive from a suspect they said was uncooperative.

The Metropolitan Police said a 29-year-old man had been arrested on suspicion of preparing an act of terrorism and on a charge of attempted murder. Local news reports identified the suspect as Salih Khater.

The authorities said they were treating the events on Tuesday as an act of terrorism, “given that this appears to be a deliberate act,” because of the location — the center of British politics — and the method used. The Houses of Parliament have been the target of terrorist attacks before, and past episodes have involved drivers deliberately steering vehicles into pedestrians.

The driver in this episode, who was swarmed by armed officers on Tuesday after the silver Ford Fiesta crashed into cyclists, pedestrians and a concrete barrier outside Parliament, was not cooperating, the authorities said.