An Israeli team has been credited for having prepared the Massachusetts General Hospital for the current influx of victims of the Boston marathon bombing.

Seventeen critically injured people are being treated at the hospital after two explosions in downtown Boston on Tuesday afternoon.

Alastair Conn, Chief of Emergency Services at Massachusetts General Hospital told reporters: “About two years ago in actual fact we asked the Israelis to come across and they helped us set up our disaster team so that we could respond in this manner.”

According to the Algemeiner, when Dr Conn was asked about the explosions, “Would you characterise these as almost something you would see in a military setting?”

He responded: “Absolutely, this is like a bomb explosion that we hear about in the news in Baghdad, or Israel or some other tragic place in the world.”

At the latest count, the attacks have killed three and injured 140.

The two devices exploded amongst spectators near the finish line.

Rabbi Mayer Zarchi from Boston Chabad synagogue was at the scene. He said: “People just started running away from the centre, from the finish line.”

“I’ve never seen anything like this before – the nature of the carnage, you can’t really articulate it in words. It was unreal.”

Abraham Foxman ADL National Director said in a statement: “Like all Americans, we were deeply shocked by the apparent bombing of the Boston Marathon. It is sad that any time a bomb explodes in public place we are conditioned as a first reflex to think of it as a terrorist attack; but unfortunately, in this instance it appears that our fears have been realised.”

When asked whether it was a terrorist attack, Boston Police commissioner Ed Davis told reporters: "We're not being definitive about this right now, but you can reach your own conclusions based on what happened."

At a briefing at the White House, US President Barack Obama said: "The American people will say a prayer for Boston tonight. Michelle and I send our deepest thoughts and prayers to the families of the victims in the wake of this senseless loss."

"We will find out who did this and we will hold them accountable," he said. "Make no mistake, we will find out who did this and why they did this, and the groups or individuals responsible will feel the full weight of justice."