Oscar Otero was barely a few feet away from the blasts that took place Monday near the finishing line of the Boston Marathon.
"You heard boom-boom, then people screaming," Boston Globe quoted Otero as saying.
"There was blood all over the place. I saw a leg, people with bones sticking out of their skin," he said.
"It's hard to describe."
Al Ghilardi, a photographer for the Boston Athletic Association, was on the bridge over the finish line when he saw a red flash.
"Then a big plume of white smoke, and then I ducked because I felt the shrapnel," Ghilardi was quoted as saying.
"I saw people in awe. They were frozen. It took a few seconds for people to recognize what happened."
Andrea George, who was across the street from the finish line, recalled: "We heard a noise and heard the glass shatter."
"...I just started running. Everyone was running in different directions. It was the scariest thing I ever saw."
Mike Smith, a mechanic, said: "I was in shock. It was like a canon going off."
"I didn't know what was going on. I didn't realize what was happening until I saw people covered in blood. I saw maimed people."