The explosives used in the Boston Marathon bombing were crude devices often called pressure cooker bombs, where pressure cookers are filled with explosives, ballbearings, nails and other shrapnel.
"The aim was to maim as many people as possible. They are based on claymore [anti-personnel] mines, where thousands of ballbearings are packed in front of explosives. The people [who use the mines] know it will maim soldiers and that it will take another three or four people to then look after that person," Dr Reti said.
"It's a very brutal way to inflict harm on people and was meant to hurt people and cause chaos."
He said there was a sombre mood in Boston yesterday as people came to terms with what had happened. Dr Reti said as he and Mr Leeming visited each hospital he was amazed that they were surrounded by SWAT teams, armoured personnel carriers and armed guards.
"I hadn't seen anything like that in the US before. I was in the UK during the Falklands War and saw armed personnel at hospitals then, but not here," he said.
"It's a reflection that the bad world has come to town. In the emergency departments you couldn't get through the doors without proper identification, so it was good to have a pair of Kiwis with the appropriate medical and diplomatic background to get us in." He said it was reassuring they did not find any New Zealand victims among the many injured, but he felt it was important that "two Kiwis" did the searching.
"I think that's what I would want if it was me, other New Zealanders looking after you on the ground. What New Zealander doesn't want to know that two Kiwis are out there looking through the hospitals for their family members or loved ones?"
Dr Reti said he also went downtown to see the area where the bombs exploded.
"I went to Park St and there was every media organisation possible there, all with their satellite dishes up broadcasting.
"Boston is sombre. As a student town there's usually a lot going on, but it's like there's a cap on the normal effervescence of the place. Boston is a very thoughtful city that thinks before it acts. There's a lot of thinking going on at the moment."