South Yorkshire's police and crime commissioner has paid tribute to the police officer killed in today's terror attack in London.
Dr Alan Billings posted a statement on Twitter after an armed police officer was stabbed by an attacker while serving in the line of duty outside Parliament.
He said: "Last week I visited at home a police officer who was attacked answering a call a year ago in Sheffield. Today we hear of an officer killed in the line of duty outside Parliament.
"We should never forget that police officers make the decision to keep us safe whatever the cost to the everyday of their working lives. And we should thank them for it.
"My prayers are for those who have died and been injured today, and those who will bear the scars for the rest of their lives."
MPs, staff and visitors kept inside Parliament during a security lockdown have since been allowed to leave.