Washington, Apr 15 (EFE).- The "full weight of justice" will fall on those found to have been behind Monday's deadly bombings in Boston, U.S. President Barack Obama said hours after two people were killed and more than 110 others wounded in explosions at the finish line of the city's famous marathon.

"We still do not know who did this, or why, and people shouldn't jump to conclusions before we have all the facts," Obama said at the White House.

"But make no mistake: We will get to the bottom of this. And we will find out who did this, we'll find out why they did this," the president said.

"Any responsible individuals, any responsible groups will feel the full weight of justice," he said.

"We're continuing to monitor and respond to the situation as it unfolds, and I've directed the full resources of the federal government to help state and local authorities protect our people, increase security around the United States as necessary, and investigate what happened," the president said.

Federal authorities characterized the incident as a terrorist attack.

Boston police said they found and disarmed two other explosive devices in the vicinity of the blasts.

The city's police commissioner, Ed Davis, said media reports that authorities had a suspect in custody were incorrect.

A fire at Boston's John F. Kennedy Presidential Library was ultimately determined to be accidental and not related to the explosions downtown.

The blasts happened within seconds of each other, according to a Boston Herald reporter who was among the 26,000 competing in the race.

The explosions occurred shortly before 3:00 p.m. as dozens of runners were crossing the finish line near Copley Square, packed with thousands of spectators and friends and family of the competitors.

Runners still on the course were called in after the explosions and authorities evacuated two hotels in the vicinity. EFE