A law enforcement official in the United States says the brothers suspected of the Boston Marathon bombings had originally planned to carry out the attack on 4 July, America's Independence Day.
The official says the Tsarnaev brothers decided to strike earlier because they completed building their bombs more quickly than expected.
It is unclear if they planned to target a specific event, but Boston hosts major 4 July festivities each year, Reuters reports.
Two bombs were set off near the marathon's finish line, killing three people and injuring 264 on 15 April.
Chechen immigrant Dzhokhar Tsarnaev, 19, is under arrest for the bombing and charged with using a weapon of mass destruction. His older brother Tamerlan, 26, was killed in a battle with police on 18 April.
Meanwhile, the body of Tamerlan Tsarnaev has been claimed by his family. The Massachusetts Department of Public Safety confirms a funeral home hired by his relatives picked up the remains on Thursday.