During rescue efforts at the school, searchers discovered an additional 500 pounds (230 kg) of unexploded dynamite and pyrotol connected to a timing device set to detonate at the same time as the first explosions; the material was hidden throughout the basement of the south wing.
A bomb disposal unit had sprung into action as soon as the first explosion happened.
About 20 minutes after the first explosions, as ambulances fought through traffic and the police shouted to control the panicked crowd, a car bomb blew up a block away, sending up a tower of flame but injuring no one.
Photograph: MetroWest Daily News/Ken McGagh/Reuters Officials react as the first explosion goes off on Boylston Street near the finish line of the 117th Boston Marathon.
She goes every year; last year we had run into each other on the same block as the first explosion.
Two car bombs exploded in rapid succession in a parking lot outside the government offices where the meeting was being held, then a suicide attacker detonated a third bomb outside the city's hospital as those injured in the first explosions were arriving.
Relatives said both had stood up in an attempt to flee when the first explosions went off as the siege reached a bloody end on Friday.
After a decade of shellfire and bombing, the first explosions were about as startling to the people living in Kabul's endless vistas of rubble as the barking of the packs of hungry dogs that roam the city at night.
Xianhua identified the owner of the warehouse involved in the first explosion as Tianjin Dongjiang Port Ruihai International Logistics.
One of my friends called, and as we talked the first explosion went off.
We heard the first explosion just as we had finished our iftar meal ending the daily Ramadan fast and settled down in front of the television.
