Four including attacker and policeman were killed in London separate attacks

In a near-simultaneous incident, a woman died and 20 other people were injured after a car plowed into pedestrians on nearby Westminster Bridge, police said.

Metropolitan police also said they are treating the parliament attack as a terrorist incident until they know otherwise.

Police gave the total number of deaths at four, but did not identify who the fourth casualty was.

Prime Minister Theresa May was taken to her residence shortly after the incidents, her office said.

Metropolitan police said the incidents led to a number of casualties and asked the public to avoid areas of central London surrounding Parliament Square.

Parliament Square is under a complete security lockdown, with all roads into the square cordoned off by police.

St Thomas Hospital said some people they are treating from the incidents have “catastrophic injuries”. At least three French high school students were among the injured, according to reports.

Met Police Commander BJ Harrington earlier appealed for public information and urged the public to stay away from the Westminster area.

In incoming international reaction, U.S. Secretary of State Rex Tillerson ​condemned the “horrific acts of violence” in a statement, saying “whether they were carried out by troubled individuals or by terrorists, the victims know no difference”.

He added, “The American people send their thoughts and prayers to the people of the United Kingdom”