An Irish American surgeon who worked at the hospital emergency room where children were rushed to after the Boston Marathon bombing has spoken of the harrowing experience.

Trauma surgeon Doctor David Mooney often sees injured children in his line of work but nothing prepared him for the wounds he saw on April 15 at Boston Children's Hospital.

'These kids were really badly hurt,' Mooney, director of the trauma center at Boston Children's Hospital, told People. 'They had soot all over their faces, burnt hair and burnt eyebrows and tourniquets on their legs that first responders had put there to save their lives and keep them from bleeding to death.'

In his line of work Mooney says that the hospital sees an average of 30 to 40 injured children a day, with the majority turning out to be less serious than originally thought. But not on April 15.

'It was really the opposite,' he says. 'It was horrible. It was hard to imagine someone would do this.'

The injuries the staff were seeing were unprecedented.

'A little girl had a lot of injuries, and nails were sticking out of her body,' he says. 'We were removing nails from the flesh in her side. That was the thing that gives you pause.'

After his wife called to tell him of the bombs Mooney went straight to the emergency room to initiate a 'code triage' and get staff prepared quickly. Although it was a holiday with reduced staff working, within an hour personnel voluntarily arrived, after parking as close as they could to the hospital and then walking the rest of the way because of blocked streets.

Hospital staff reportedly treated ten patients, three of whom were severely injured. Eight year old Martin Richard was killed in the blast and was not a patient at Boston Children's, says Mooney.

'I wish he would have made it to us so we could have had a shot at saving him,' Mooney says.

Of the three critically injured patients (a 2-year-old boy with a head injury, a 10-year-old boy with multiple leg injuries and a 9-year-old girl with a leg injury) two are expected to have more surgeries. The other seven patients have been discharged.

'These kids will live, they have things that can be fixed,' Mooney says.

A father of four himself, Mooney says that parents can really reassure their kids by talking to them about the tragedy and the explosions.

'You can reassure them that while bad things do happen, ninety-nine percent of the world is good.'