The British Parliament is in lockdown after a police officer was stabbed and witnesses reported seeing a car hit a number of pedestrians in a serious and still unfolding incident in central London that police are treating as a terror attack, the UK media reports.

One woman has been confirmed killed and other people are being treated for “catastrophic” injuries, the British news agency Press Association reported, citing a junior doctor at a central London hospital.

The UK police asks public to stay vigilant. The operation is going on.