Responders from the RNLI could be seen treating casualties at Westminster pier.
A police boat carrying armed officers has crashed near Westminster Bridge in central London, police sources have said.
Casualties could be seen being treated by paramedics on a rigid black inflatable boat moored to the side of the river.
Officers have taped off a section of the bridge overlook the Houses of Parliament.
A large number of police officers, fire crews and ambulances are on the scene, with traffic across the bridge at a standstill.
A Port of London Authority spokesperson said: “We are aware of an incident involving a police vessel at Westminster Bridge.
“We are supporting the response and providing assistance where needed, working closely with the Metropolitan Police, HM Coastguard and partner agencies to manage the situation.”
A police helicopter and an air ambulance were circling above.
Entrances three and four to Westminster Underground station have been shut, Transport for London has confirmed.
