Survivors tell of carnage at Marathon finish line

With their harrowing testimony at times illustrated by photos and videos, survivors of the Boston Marathon terror bombings broke into tears Wednesday in federal court in Boston as they described the chaotic moments after two bombs exploded near the finish line on April 15, 2013.

One of the blasts left Sydney Corcoran bleeding from a leg wound and cost her mother, Celeste, both of her legs.

Testifying on the first day of the trial of Dzhokhar Tsarnaev, who allegedly planned the bombing, Sydney Corcoran testified that she was outside the Marathon Sports store with her mother and her father, Kevin, as they waited for a relative to cross the finish line when one of the blasts went off.

The explosion shrouded Boylston Street in smoke, making it impossible for her to see anything. But she could hear, she said.

“You just hear the stifled screams of people you can’t see,’’ said Corcoran.

A piece of shrapnel had pierced an artery in Corcoran’s leg, and she began to bleed profusely.

“I was dying. The blood was leaving my body, I was bleeding out, I had minutes,’’ she testified. “I remember thinking, this is it, I’m going to die. I’m not going to make it. And I remember feeling I was going to sleep.”

Strangers stepped in to staunch the bleeding, while her father tried to help her mother. “He could see my eyes going white. I was getting increasingly cold. I knew I was dying,’’ she said.

Sydney Corcoran testified she rode to a Boston hospital convinced she was now an orphan. However, her mother survived and escorted her out of the courtroom Wednesday, walking on her two prostethic legs.

Karen McWatters went to the Marathon with Krystle Campbell, one of three people killed in the bombing. She testified Wednesday that they were standing next to each other when the bomb detonated. McWatters leg was damaged by the explosion.

“I knew something was wrong with my leg,’’ said McWatters, who has married since the bombings. “I screamed and waited for help.”

McWatters said she managed to make her way to where Campbell lay on the ground. They held hands, and Campbell said her legs were hurting, McWatters recalled.

“Her hand went limp in mine,’’ McWatters testified, “and she never spoke again after that.”

Rescuers then arrived, she said. “They pulled Krystle away from me and started to do CPR,’’ she said. “It seemed really bad.”

Celeste and Sydney Corcoran.John Tlumacki/Globe Staff/Boston Globe

On the stand, McWatters was shown a photograph of the scene.

McWatters was rushed to a Boston hospital where initially she was believed to be Campbell because she had her friend’s cellphone. Campbell’s family thought she was in surgery, and that McWatters had been killed. The confusion only ended when Krystle’s parents walked in to her hospital room and saw McWatters.

McWatters eventually lost her leg below the knee.

Rebekah Gregory was near the finish line with her 5-year-old son, Noah, who was sitting on her feet as they watched runners cross the finish line when the bomb detonated. Gregory was part of a group of nine family members and friends who were there to support a relative in the race.

When the bomb exploded, it ripped off the lower part of her left leg. Her son had a BB drilled into his body.

Knocked to the ground, Gregory said, she was stunned by what she saw when she opened her eyes.

“My bones were lying next to me on the sidewalk,’’ she said. “I felt that was the day I would die.’’

She said she looked to her right and saw Campbell. “I saw Krystle Campbell, and she was dead,’’ said Gregory, who eventually had her injured leg amputated after 17 surgeries.

The blast was recorded by Colton Kilgore, also a member of the group. Jurors were shown portions of Kilgore’s video during Wednesday’s trial.

He told jurors not just what he saw, but also what he smelled.

“The smell — smoke, gunpowder, flesh — just acrid and disgusting,’’ he said, adding that the video he took captured images of a “lot of chaos, a lot of people on the ground. Smoke, shrapnel.”

The 21-year-old Tsarnaev faces 30 charges, including 17 that carry the possibility of the death penalty, in the April 15, 2013, bombing. He and his older brother, who was later killed in a confrontation with police, also allegedly killed an MIT police officer several days after the bombing.

Tsarnaev’s attorney on Wednesday, the first day of the trial, acknowledged that he had played a role in the bombing, but said he had been under the sway of his brother, Tamerlan.

Below is video from an in-store camera at Marathon Sports, with store manager Shane O’Hara circled.

Prosecutors showed footage from a surveillance camera at Marathon Sports during the first day of testimony in Dzhokhar Tsarnaev’s trial. Shane O’Hara was the manager of the sports store when the bombs went off.

Prosecution shows footage from Marathon Sports surveillance camera during the Dzhokhar Tsarnaev trial. Shane O’Hara, was the manager of the Marathon sports store when the bombs went off.