About 30 strong, members of the Montgomery County Road Runners who had qualified for the 117th Boston Marathon gathered near the start line in Hopkinton, Mass., for a group photo Monday, all smiles and nervous anticipation of the task that lay ahead.

Within hours, one of the highlights of their year had turned to chaos when two bombs went off near the finish line of perhaps the most prestigious footrace held in the United States each year, killing three and injuring more than 100.

“These are happy events,” said Dan DiFonzo, a member of the club who was running in his ninth straight Boston Marathon. “These are events we train for our whole lives. To have something like this happen on the Super Bowl of marathoning, it’s sickening. It just makes you sick to your stomach.”

Added 50-year-old Barry Hauptman of Bethesda, who had planned to celebrate his birthday as well as a fine performance in the race Monday night: “I ran the marathon, I had a great time, I loved everything, and within an hour everything was turned upside down. It’s my favorite day and to have something like this happen on the most sacred day [of the running calendar] is nothing short of flabbergasting.”

DiFonzo and others said all club members appeared to be safe. With phone service overwhelmed, runners were checking in via text message and the club’s Facebook page, telling family, friends and each other they had survived the unthinkable.

Mapping the hunt for Boston Marathon suspects

For DiFonzo, Hauptman and many others, hard training and natural speed meant more than just a fast time Monday. The bomb went off shortly before the 4:10 mark of the race; having completed the course in just over three hours, they were safely out of harm’s way.

Others faced a closer call. Giovanna Tosato, another club member from Bethesda, said she was 50 to 100 yards beyond the finish line, receiving her finisher’s medal, when the first explosion boomed out.

“It’s good that I ran a good race today, that the weather was nice,” the 64-year-old said of her 3:57 finish. “You never know with the marathon. A minute. Two minutes.”

Sarah Johnson, 42, of Bethesda, said she was on the 23rd floor of the Marriott hotel in Copley Square, about a block from the finish line, when the first bomb went off.

“I was in my hotel room and just heard a loud explosion, kind of like an old-time cannon,” she said. She went to the window in time to see “a big poof of smoke;” then the second bomb went off.

“My first thought was ‘Oh this is Boston.’ I hoped it was a reenactment of some kind. Then she saw “spectators running” toward her hotel, “just running.”

Bob Yarchoan, 62, who finished earlier than his wife, Tosato, was farther from the blasts. The couple was reunited at their hotel and now Yarchoan said he worries about security at future marathons.

“Terrorism is inexplicable anyway,” he said. “But why someone would do this to a marathon — it’s going to have major repercussions . . . on the big ones.”