A police vessel carrying armed officers crashed near Westminster Bridge on the River Thames, with casualties treated by paramedics on a rigid inflatable boat as emergency crews respond. Entrances to Westminster Underground station (three and four) have been shut, and traffic on the bridge is at a standstill as responders secure the area along Embankment. A large police presence, plus fire crews, ambulances, helicopters, and an air ambulance, are on scene, with the Port of London Authority coordinating river traffic management and working with the Metropolitan Police and HM Coastguard. Investigations and updates are ongoing as authorities provide updates to the public. Eyewitnesses and media have described the scene as rapid and evolving, with multiple agencies involved in managing the incident. More details are expected as the situation develops."