A motorist slammed into pedestrians and cyclists near Britain's Houses of Parliament on Tuesday and police are treating the incident as an act of terror.

A man in his 20s was arrested on suspicion of terrorist offenses after the silver Ford Fiesta collided with rush-hour commuters before slamming into a barrier. Two people were hurt, but authorities said none of the injuries is life-threatening.

Armed police swooped into the area, cordoning off streets surrounding the heart of Britain's government. Police appealed to the public to stay away, and the Westminster subway station was closed.

Several eyewitnesses said the driver's actions were deliberate.

"The car drove at speed into the barriers outside the House of Lords. There was a loud bang from the collision and a bit of smoke," Ewelina Ochab told The Associated Press. "The driver did not get out. The guards started screaming to people to move away."

Jason Williams also saw a car moving at high speed.

"It looked deliberate. It didn't look like an accident," he said. "How do you do that by accident? It was a loud bang."

The incident heightened tensions in a city that has seen four vehicle-based terror attacks in less than 18 months.

The area was the site of a terror attack in March 2017, when Khalid Masood ploughed a car into crowds on Westminster Bridge, killing four people. Masood abandoned his car and then stabbed and killed a police officer before being shot dead in a courtyard outside Parliament.

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