Boston, MA MSNBC --- Two explosions went off near the finish line of the Boston Marathon on Monday as runners were finishing the race, injuring 150 people.
At least three people have been confirmed dead, including an 8 year old boy. Officials also say some of the victims have lost limbs due to the explosions.
"I am not prepared to say we are at ease at this point in time," Boston Police Commissioner Ed Davis said at a briefing six hours after the attack transformed the celebrated race into a blood-spattered crime scene.
Video from the finish line showed screams and an enormous cloud of white smoke, and about 20 seconds between the blasts.
Jackie Bruno, a reporter for New England Cable News, said on Twitter that she saw people’s legs blown off.
“Runners were coming in and saw unspeakable horror,” she said.
NBC affiliate WHDH said that storefront windows nearby were blown out.
Runners who were still on the 26.2-mile course were being stopped and directed elsewhere, the Massachusetts Emergency Management Agency said. The agency suggested that people trying to reach loved ones use text messaging because of crowded phone lines.
During a news conference Monday, President Obama said they are still in the investigation stage and do not want to jump to conclusions. However, the President did say that those responsible will be held accountable for this tragic incident.
Authorities say that no other explosive devices have been found and that the only explosives on the scene were the two that went off during the race, causing this tragedy.
The FBI is also asking anyone who was taking pictures or video around the area of the explosions, to send that evidence to authorities to help in their investigations.
About 12 blocks of downtown Boston have been blocked off in what the police are saying is their biggest and most complex crime scene they've ever dealt with.
Boston police have issued an alert for a rental van that may have sought access to the marathon route, and another alert for a man wearing dark clothing and a hood who was seen leaving the scene of the blasts.
The race is a signature event in Boston. Race organizers said that almost 27,000 runners competed, representing 96 countries. Tens of thousands of spectators turn out each year to watch.