LONDON -- London's Metropolitan Police service said Tuesday that a man was in custody after driving a car into a gate outside the Houses of Parliament in the British capital, injuring "a number of pedestrians." It remained unclear whether the crash was intentional. Police said they were "keeping an open mind," but noted that the counter-terrorism division was taking the lead in the investigation. Streets in the area surrounding the British legislature were cordoned off and closed to traffic during peak morning rush hour and there was a heavy police presence. London's ambulance service said it treated two people at the scene that they were taken to an area hospital for further evaluation, but their injuries were not believed to be serious. At least one witness told British television that they saw the car driving toward Parliament at high speed. "I think it looked intentional - the car drove at speed and towards the barriers," Ewalina Ochab told Britain's Press Association. "I was walking on the other side (of the road). I heard some noise and someone screamed. I turned around and I saw a silver car driving very fast close to the railings, maybe even on the pavement," she said. Several cyclists were seen immediately after the crash, laying in the road with apparent injuries. Witnesses said the car drove into a group of cyclists before crashing into the parliament gate. Police at the scene told CBS News it was an ongoing incident. The vehicle involved, a small silver hatchback, could be seen smashed into a security barrier at a vehicle security checkpoint in the parliament perimeter fence. Police said in a tweet that Westminster station on the London Underground, or Tube network, was closed to entry from outside. The station, the closes to the Houses of Parliament, was only operating for internal transfers. The crash comes about a year and a half after a terrorist drove his car into a number of people outside parliament and then attacked others with a knife, leaving a total of four people dead. Police said Khalid Masood -- a 52-year-old Briton with convictions for violence who had spent several years in Saudi Arabia -- was believed to have acted alone in the attack, but that he may have been inspired by others. The Islamic State of Iraq and Syria (ISIS) claimed Masood was a "soldier" responding to its repeated calls for attacks on western nations. Police said, however, that they found "no evidence" of any links to ISIS or al Qaeda. Masood was killed by police after fatally stabbing an officer and running down pedestrians with his rented SUV. It was the deadliest extremist attack in Britain in 12 years. © 2018 CBS Interactive Inc. All Rights Reserved.