The Boston Marathon explosion is the most significant event to happen to U.S. history since 9/11. With one suspect dead and another in federal custody, U.S. officials now believe the terrorist brothers had more than one attack planned before being caught days later. Some believe Times Square was targeted as the next explosion site.

After catching younger brother, Dzhokhar Tsarnaev, the Boston police discovered a much larger arsenal of weapons than they originally anticipated, leading authorities to believe there was more than one attack planned.

Boston and federal authorities did their best to capture Dzhokhar Tsarnaev alive so they could find out more information regarding other planned attacks, while trying to uncover any other suspects who may have aided in the Boston Marathon explosion.

During the two nights leading up to Tsarnaev's capture, the younger [more "impressionable"] brother sustained gunshots to the throat during a shootout that left one Boston police officer dead.

19-year old Dzhokhar Tsarnaev was in critical condition but stable, according to Boston police Commissioner Ed Davies.

"The suspect is in critical but stable condition. There is a special interrogation team from the Federal Bureau of Investigation standing by to talk to him. That hasn't happened it. Until it does and until the investigation moves forward we won't know definitely what other things may come."

During the same shootout that Tsarnaev was shot in the throat, his older brother Tarmelan Tsarnaev, 26, was allegedly killed by police gunshots. The case is still fresh, but some experts believe Tarmelan wasn't killed until his 19-year old brother drove over his wounded body when trying to escape.

Motives for the April 19 Boston Marathon explosion are still unknown. So far the death count is at 3 people [one child] and over 180 injured in the attack.

Live footage of the Boston Marathon explosion. Viewer discretion advised.