Tuesday marks the one year anniversary of the Boston Marathon bombing, when two Chechen brothers allegedly planted pressure-cooker bombs near the race’s finish line, killing three people and wounded more than 260.
It was the worst bombing on U.S. soil since security was tightened after the attacks of September 11, 2001, and it occurred on a day when tens of thousands of spectators packed the streets to watch the world-famous race.
One of the brothers, Tamerlan Tsarnaev, died after a gunfight with police while he and his brother were trying to flee Boston several days after the attack.
His younger brother, Dzhokhar Tsarnaev, is awaiting trial on charges that could lead to the death penalty if he is convicted.
Many runners were heading for the finish when a fireball and smoke rose from behind cheering spectators and a row of flags representing the countries of participants, video from the scene showed.
The cheers turned to screams and panic.
Ambulances, fire trucks and dozens of police vehicles converged at the scene, and spectators could be seen crying and consoling each other.
The bombs killed three spectators: Martin Richard, 8, Krystle Campbell, 29, and Chinese national Lu Lingzi, 23. Prosecutors charge that the Tsarnaev brothers shot dead a fourth man, 27-year-old Massachusetts Institute of Technology campus police officer Sean Collier, a few days later, in a failed attempt to steal his gun as they tried to flee the city.
Boston officials vowed on Saturday (April 12) to balance tight security with a feeling of fun at the coming Boston Marathon, the first running of the world-renown race since the bomb attack.
Officials advised residents and visitors to expect a large police presence through the week leading up to the April 21 race, starting with a memorial service attended by Vice President Joe Biden on Tuesday, the one-year anniversary of the attack.