The BBC cited police as saying that four people, including an armed police officer and a man believed to be the attacker, died in the attack on Wednesday afternoon. Twenty people were seriously injured, according to media reports.
Britain's most senior counter-terrorism officer, Mark Rowley, said the attack started when a car was driven over Westminster Bridge, near parliament, hitting and injuring a number of members of the public.
After the car crashed, a man armed with a knife "continued the attack and tried to enter parliament," Rowley said.
The telegraph.co.uk website reported that an attacker had mowed down pedestrians and stabbed an officer before being shot by police.
Britain’s Daily Mail reported that PM May had been bundled into a car and rushed away from the House of Commons by police.
May and Jarosław Kaczyński, the head of Poland’s governing conservative Law and Justice (PiS) party, had been due to talk about future negotiations on the UK's divorce from the European Union, bilateral relations between London and Warsaw, European security and cooperation within NATO.
Beata Mazurek, a spokeswoman for the PiS parliamentary club, said Kaczyński and his delegation were safe.
Kaczyński and May had been due to meet at Downing Street at around 4:30 pm CET.
The Polish embassy in the UK appealed for caution and said that the Polish consul in London was monitoring the situation and checking if any Poles were injured in the attack.
"In connection with the evacuation of the area around parliament in London we are calling for people to be additionally cautious and adhere to police instructions," the embassy tweeted.
“The Consular Section of the Polish Embassy in London remains in contact with the police," the statement on Twitter added.
Ryszard Terlecki, the head of the PiS parliamentary club, said Kaczyński would stay in London until Thursday, when there was a possibility that he would meet PM May.
Wednesday's attack in the British capital took place exactly a year after attacks by Islamic militants killed 32 people in Brussels.
(pk)
Source: PAP/IAR/TVP Info