London terror attack: Several arrested after raid

Seven people have been arrested in a raid on a Birmingham flat, following a terror attack in Westminster which killed four people and injured at least 29 others.

One of those killed was the attacker, who was shot dead at the scene, while local police say seven of those in hospital remain in a critical condition.

Heavily armed police have been conducting raids in six addresses since around 10:30pm on Wednesday (local time).

In a press conference on Thursday morning, local police said they believe the attacker acted alone and was "inspired by international terrorism".

"To be explicit, at this stage we have no specific information about further threats to the public," says Met Police Acting Deputy Commissioner Mark Rowley.

Investigation into the attacker's motives, preparation and association is still continuing. Local police have yet to name the attacker, but believe they have identified him.

Police have increased the number of officers on the streets, both armed and unarmed, in the wake of the attack.

"[We're] working very hard to reassure the public and London can go back to its own business," Dep Cmsr Rowley said.

"We must not allow terrorist to sow discord and fear in our city."

A car believed to be linked to the attack, which ploughed into pedestrians near the Houses of Parliament, was reportedly rented from a business near Birmingham last week.