At least two people were killed and scores injured following multiple bomb explosions at the Boston Marathon on Monday.

NBC News reported that small home-made bombs were responsible for the blasts. Intelligence officials said two more explosive devices were found and that authorities had begun dismantling them.

Speaking to the nation early Monday evening, President Obama vowed to bring the perpetrators of the bombing to justice. He did not refer to the blasts as terrorism.

“We still do not know who did this or why and people should not jump to conclusions before we have all the facts,” Obama said. “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. Any responsible individuals, any responsible groups will feel the full weight of justice.”

But officials are still in the investigations stage, Obama said.