MP Tobias Ellwood attempted to give mouth-to-mouth resuscitation to the police officer stabbed just outside Parliament. The officer is now reported to have died, according to the BBC.
Ellwood also tried to stem the blood flow by applying pressure on his stab wounds, the Telegraph reports.
The MP, who is a former soldier, waited with the injured officer until the air ambulance landed in Parliament Square, and was later seen with blood on his hands and face.
Ellwood, who lost his brother in the Bali terrorist bombings in 2002, talked to officers before returning to the Foreign Office.
One suspect was shot by police after stabbing a police officer inside the grounds of Parliament.
At least four people have died and many are injured after a car drove into dozens of people on crowded Westminster Bridge. The Metropolitan Police are currently treating the incidents as terrorist attacks.