Marathon Monday was shaping up as a banner day for former Patriots guard Joe Andruzzi and his namesake foundation.

The foundation, which aids families dealing with cancer, had 21 runners who raised $163,000 entering the Marathon. It was hoping to raise even more at a watch party just a few blocks from the finish line at Forum restaurant, 755 Boylston St. The sun was shining, and people from the foundation and sponsors were hanging out on the patio.

“Everybody was having fun; we were having a grand old time,” said Andruzzi, a cancer survivor. “We had some patients there that were a part of the foundation, one of our patients’ dads was running and their siblings and mom were having fun. We had a lot of people, from upstairs to downstairs and all over the place.

“It was starting out to be a great day, great event. Unfortunately it did not end up that way.”

Andruzzi, his wife Jen, and a photographer left the party at about 2:45 p.m. and walked to the finish line area to celebrate with their runners.

“We found one and were looking for the next and all of a sudden that first explosion happened,” Andruzzi said. “It was loud, you felt the effects. In that instant, nobody knew anything. There were some screams and yelling and a lot of smoke. You didn’t know if it was coming from a restaurant, kind of like a kitchen [explosion]. Then about 10-15 seconds later there was the second explosion. Then mayhem just started.”

Andruzzi helped two runners to their feet when he saw a blood-covered man being aided by others and brought him to the medical tent. That was the first of two times Andruzzi would lose contact with his wife and photographer.

Andruzzi then arrived back at the scene of the first blast.

“There was just chaos, like a battle scene,” he said. “No words can describe it.”

After helping to move some of the spectator fencing, Andruzzi found his wife and was walking back to Forum.

“I turned and saw three young women carrying somebody on their back,” he said. “I ran over and that’s the picture you saw. I told them, ‘Let me help.’ Scooped her up and I remember them yelling at the cameraman, ‘Stop taking pictures of my mom.’ I walked her down the block and to an ambulance. Later I was talking to her, she was calming down. She had hurt her ankle. One of the kids had blood on their hand, must have gotten hit with something. She said she was fine, a little scrape and EMS was there and they were taking care of her.”

Andruzzi doesn’t know the name of the woman in the photograph, just that she and her three daughters were from Virginia and apparently looking for her husband, who was in the race.

After losing track of his wife again, Andruzzi walked back to Forum through the back alley between Newbury and Boylston Streets, but he couldn’t get close to the restaurant.

Andruzzi was informed by restaurant staff that the place he had just left, with dozens of his foundation’s revelers filling it from top to bottom, was now a crime scene because the second bomb detonated directly in front of the establishment.

“My heart just dropped,” Andruzzi said. “I was sick to my stomach. We basically had the whole place to our foundation and 90 percent of the people were part of the JAF. We were worried sick about what was going on.”