LONDON (March 22): One woman has died and other people are being treated for "catastrophic" injuries after an attack near parliament on Wednesday, British news agency Press Association reported, citing a junior doctor at a central London hospital.

Reuters reporters inside Parliament heard loud bangs and shortly afterwards a Reuters photographer said he saw at least a dozen people injured on Westminster Bridge, next to Parliament, in what police said they are treating as a terrorist incident.

Meanwhile, the US State Department said on Wednesday it was closely monitoring the "concerning situation" near to Britain's Houses of Parliament and offered to assist in any way after a policeman was stabbed and several people injured in an attack.

State Department spokesman Mark Toner urged Americans in London to contact their families to let them know they are safe.

"We stand ready to provide all possible consular assistance should we become aware of any affected US citizens," he said in a statement.