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A witness, Mark Ashbridge, took this picture of the small blast in Belfast city centre.
It appears people had been pushed back before the explosion occurred.
Mark says "the glow is the result" of the blast:
No injuries have been reported.
Parents are assembled outside Arapahoe High School in Colorado waiting for news of their children, according to a reporter from local newspaper Denver Post.
The gunman at Arapahoe High School in Colorado was looking for a specific teacher when he was confronted by a student, local media has reported.
Local police have said a gunman has been found dead at Arapahoe High School in Colorado with a self-inflicted gunshot wound.
Two people, excluding the gunman, have been confirmed as injured after several shots were heard fired at the school in Centennial.
Denver Post reporter Ryan Parker has tweeted several images from the cordoned off Arapahoe High School in Colorado amid the ongoing alleged shooting incident at the school.
School staff and volunteers are hurriedly trying to get names of students who are outside of school http://t.co/GPYoygZvvI
BREAKING: Hospital spokesman: 1 student in critical condition after Colo. high school shooting reports
Hundreds of people have been evacuated from a Colorado high school following a shooting, according to the Denver Post.
A student at the Colorado high school where the alleged shooting has taken place has told a Denver Post reporter she heard three shots:
Students said they hid in the corners of dark classrooms until they were led out of classrooms.
"I was scared and shaking," one student said. She heard, "bang, bang, bang" and by the third shot she was on the ground.
The local US police department has said all schools in the city of Aurora have been "placed on lock down as a a precaution" after reports of a shooting at a high school:
ALERT: Due to the incident at Arapahoe High School in Centennial all public schools in the City of Aurora have been placed on lock down as a precaution.
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