Five people, including a police officer and the attacker, died in an attack in London Wednesday.

London's Metropolitan Police say the attacker drove over Westminster Bridge, near the Houses of Parliament, killing two people and injuring dozens of others, before crashing into the railings outside Parliament.

Then the attacker, who had a knife, ran to Parliament and was confronted by police. An officer, who wasn't armed, was fatally stabbed. The attacker was then fatally shot by officers who were armed, Metropolitan Police said.

At a news conference Wednesday evening, Metropolitan Police said roughly 40 people were injured, including three police officers, but noted that number could change.

Prime Minister Theresa May called the attack "sick and depraved," according to the BBC. Leaders from around the world have condemned the attack, including President Donald Trump.

The attacker hasn't been identified, and earlier in the day officials said they were treating the incident as a terrorist attack until they know otherwise.

For more, you can read the original story from Wednesday morning below. 

Shots have been fired and casualties reported in what police are treating as a terrorist incident outside the U.K. Parliament buildings in London.

The BBC reports a police officer was stabbed outside the Houses of Parliament in Westminster, with the alleged assailant then shot by armed police.

Several people are also reported injured after being "mowed down" by a vehicle on nearby Westminster Bridge. It's not clear at this stage if the police officer's assailant was also the driver of the vehicle, but the incidents are considered related.

British MP Barry Sheerman tweeted a woman hit by the car on the bridge has died.

The London Evening Standard reports four shots were heard after the SUV crashed into the railings on the bridge.

U.K. politicians were ordered inside Parliament by armed security, and the Parliament and nearby buildings have been placed on lockdown as authorities respond to the incident.

The incident was reported at 2:40 p.m. GMT (9:40 a.m. central time), with road and rail traffic to the area diverted away.

London's Metropolitan Police says it is treating it as a firearms incident as well as a "terrorist incident, until we know otherwise."