Boston Marathon Blasts: 8216;After running 26 miles,I wasnt going to give up8217;

The two blasts occurred within seconds on a sidewalk along the 42-kilometre route of the marathon,where thousands of people had lined up to cheer on the marathoners Monday.

Video and pictures from the scene show Iffrig,in bright orange vest,on the ground,trying to get up.

With the help of a race official who lifted him to his feet,he got up and kept going,determined to reach his goal. I got down to within 15 feet of the finish apron and just tremendous explosion, he told CNN. The shock waves just hit my whole body and my legs just started jittering around, he said.

But,he said after running 26 miles,he wasnt going to give up.

Iffrig,who sustained a scrape on his knee,described his proximity to the blast as scary.

His son,Mark,said Iffrig was a bit dazed by the blasts. He said it was quite a concussive blast.

US media reports say Iffrig,a retired builder from Washington state,took up running in the 1970s so he could stay fit enough for mountain climbing.

He is an accomplished runner,and in 2009 was named the Washington Heralds Man of the Year in Sports.

Another witness said he felt the explosions were so powerful that he thought it came from a cannon. It felt like a huge cannon, a witness said.

Steve Silva,a sports producer with Boston.com said his camera kept rolling amid screams of shock and horror.

It was just immediately evident there were injuries,right in the middle of the spectator crowds. I saw dismemberment,I saw blood everywhere, Silva said.

I saw someone lose their leg,people are crying,people are confused.

Allan Panter,a doctor who was near the finish line waiting for his wife to finish the race,said he was standing about 20 to 25 feet from the first blast. He said he treated victims on the street after the explosion.