University of Sheffield students and staff are currently being held inside a Westminster building after an attack outside Parliament.
A group of about 40 from the university's journalism department are in lockdown in Portcullis House after this afternoon's incident.
A policeman has been stabbed and his apparent attacker shot by officers. Around three shots rang out outside the Palace of Westminster after a man ran through the gates into the front yard of the parliamentary compound apparently waving a knife.
One woman has died, according to the Press Association, with others suffering 'catastrophic' injuries.
Lydia Chantler-Hicks, a 22-year-old masters student, said the group had been in the main atrium of the building when they heard shouting.
"People were running in and closing the security doors at the entrance where we came in," she said.
"We heard what we think may have been a gunshot and there was some confusion.
"We heard shouts of 'armed police' and everyone started moving to higher levels.
"We were instructed to get right to the back and stay away from the glass."
Lydia said the group was unsure what had happened but had heard a police officer had been stabbed and several people had been run over.
But she praised the actions of the emergency services in the confusion.
"Everyone in charge was very calm - there was no shouting," she said.
"So we are all feeling concerned for the people outside, but just glad that we are all safe. We just want to know what's happening."
Lydia said she could see emergency vehicles at both ends of Westminster Bridge, and the London Eye appeared to have been stopped with people inside it.
Joint head of the journalism department Marie Kinsey said the group 'didn't see much' of the incident but were aware something 'of a serious nature' was happening.
"Our priority was to make sure everybody was safe," she said.
Lecturer David Holmes said the group did get split up in the immediate aftermath of the incident but everyone had now been located and was safe.
"In the first few minutes everyone was incredibly calm and listening to instructions and keeping safe," he said.
"As you can imagine, when you start talking to people individually, you reflect on what's happening and you can get a bit emotional about it.
"But everyone has been really mature in the circumstances. Everybody in this building is."
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