A 12-year-old Martinez boy injured in the Boston Marathon bombings is recovering in Boston Children's Hospital after being struck in the leg by a piece of shrapnel, family friends said Monday.

The family is part of a Bay Area running contingent left shaken by the explosions that killed three and injured more than 100 at the venerable sporting event.

The boy was waiting at the finish line for his mother, 40-year-old Katherine Hern.

"He was very excited for his mother," said Gay Gerlack, a former Martinez city council candidate and friend of Hern.

Moments later, the child was standing with his father, sister and family friends when he was hit in the thigh by a piece of shrapnel after the first explosion went off on the north side of Boylston Street. Neither his family nor their friends were injured.

The boy was taken to Boston Children's Hospital, where he underwent surgery to remove the shrapnel.

"There were so many children that were hurt," Gerlack said. "We feel very lucky that he's going to come out of this."

Speaking on the phone from the safety of his Boston hotel, Bob Anderson could still hear the sirens outside. Hours earlier, the Los Altos resident and founder of Runner's World magazine had been among the terror-stricken competitors to hear bombs go off near the finish line.

At the time, Anderson, 65, wasn't sure where his son Michael, 37, was -- just that he'd be finishing right about the time of the explosion. When the two finally reunited in their hotel lobby, it was a teary scene.

"Oh, my gosh, the emotions just cried out,'' Anderson said. "It's just unbelievable because of the emotions -- your entire body is on edge anyway because you just ran a marathon. Then for this to be unfolding was just unbelievable. It was a scary, scary moment."

Los Gatos masters marathoner Christine Kennedy received more than a dozen texts asking if she was OK after the race. She didn't know why because Kennedy, 58, was in a subway with her daughter during the explosions.

"Of course, I am," she thought after running the fastest Boston race of her life in 2 hours, 55 minutes, 4 seconds.

Brentwood elementary school teacher Megan Faulkner ran the race in tribute to her father, who turned 80 this year, and she was emotional as she stood with him in the family meeting area, about half a mile from the finish line. That's when they heard the explosions.

Faulkner said the explosions shook the ground, but that people did not immediately know what was happening.

"We were unsure at first exactly what happened, but then all of our friends started texting us to make sure we were OK," she said. "The transit is closed underground, and you just have people kind of wandering around and trying to figure out where to go or what they should do."

Pleasanton resident Nancy Morehead finished the race four minutes before the first explosion took place.

"I heard it and I felt it. It shook the ground," said Morehead. "I wasn't very far past the finish line and I turned around and saw the big cloud and all I could think was, 'Just keep moving.'"

Morehead, who works as an analyst for East Bay Regional Parks Police, said the first explosion was so loud, she expected to see a building collapse.

Instead, she said, she saw a huge puff of smoke encompass the street.

Her cousin, Lynn Olavarri, of Scotts Valley, finished ahead of her in the race and was concerned about Morehead, she said, because she knew her average time would be around four hours and 10 minutes.

Morehead finished at four hours and five minutes -- four minutes before the first bomb exploded.

"Luckily, I continued to push toward the end even though my calf was cramping and I thought about slowing down," she said of her 43rd marathon race. "I am very thankful that I didn't."