An eyewitness to the what British police are calling a terrorist incident that has London's Palace of Westminster on lockdown has described scenes of chaos that are likely to result in many fatalities.

A medical professional working at St. Thomas' Hospital, which overlooks both the Houses of Parliament and Westminster Bridge, as told TheStreet that at least six or seven people are likely to have been killed by a driver who is suspected of deliberately targeted pedestrians.

She also said that many more could have been injured and that the Accident and Emergency department of the hospital has been placed on high alert and that hospital staff have been told not to leave the building. 

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Britain's parliament remains on lockdown after police allegedly shot and killed an attacker who stabbed a law enforcement officer outside the Palace of Westminster. Lawmakers have suspended sessions for the remainder of the day and several media outlets are reporting people were also injured along Westminster Bridge, which runs adjacent to the Parliament.

Video footage, taken along Westminster Bridge by an onlooker and broadcast by the BBC, appeared to show at least five people begin treated for injuries along the busy roadside, with eyewitnesses saying a car deliberately targeted pedestrians. An air ambulance has landed in Parliament Square and its attending to the injured along the Bridge.

The incident comes only hours after U.K. Prime Minister Theresa May held her weekly question-and-answer session with opposition lawmakers in the Houses of Parliament, a session that is typically attended by nearly all members of the sitting government.

It also follows an attack on female soldiers at Orly Airport in Paris Saturday in which the attacker, 39-year-old Ziyed Ben Belgacem, was shot and killed by military police.

Belgacem, who was born in France to Tunisian parents, grabbed the soldier in Orly's southern terminal on Saturday morning, put a gun to her head and seized her rifle, saying he wanted to "die for Allah". The attacker also fired at police officers earlier in the day in a northern Paris suburb.