Virginia Tech: Students in lockdown
Two people have been shot dead on the campus of Virginia Tech university in the United States - the site of the worst campus shooting in the US four years ago.
Police have swarmed the campus looking for the suspect who escaped on foot.
Students at Virginia Tech have been sharing their experiences with the BBC.
I was here during the shootings in 2007 as a freshman and I'll be graduating with my masters degree in a few months and I've now experienced a second round of shootings.
I, and about five others, were in an engineering lab.
The first we knew was when we heard sirens around the campus.
We then started to get text messages via the new security system, telling students to stay where they were and stay away from windows. Doors and windows all in lock down.
I'm in my dorm and when the alert went off there was a large siren across campus.
There were police cars surrounding our building and police were going through all the dorms.
The police cars have gone and we're still under lockdown.
Lockdown started at 12.30. It's been two-and-a-half hours.
We've had false alarms like this and I thought it might be anbother false alarm.
I was in the library. After the last time there are electronic plaques on the walls that say things like lockdown and they started buzzing saying there had been gunshots fired - stay inside.
There were rumours - a gunman on the loose, someone had been shot.
There is a big parking lot where the freshmen usually park their cars and we heard there was a shooting.
There were tonnes of cops with guns. It seemed like they were surrounding a building.
Everyone was on the common floor around the big TV. It was a very worrying and hectic time.
Now it is a bit calmer. We had no cell services for a while. Everyone was trying to make calls at the same time.
It's a bit of a panic knowing you are not far from where someone got shot.
We found out while we were all having a bit of a Christmas buffet. Everyone's phones went off with the Virginia Tech alert. Colleagues were updating us with what was happening.
Cell phones are a bit overwhelmed here at the moment.
I feel a bit safer under the lockdown. Looking out of the window there is no-one around. For the moment, we are just getting on with some work.