Whoever set off the explosions at the finish line of the Boston Marathon on Monday "messed with the wrong people," Tagg Romney said.

"It's such a cowardly act, whoever did this," Romney told CNN's "Starting Point" Tuesday morning. "Then you see the warmth of the first responders, and the people around who rushed to the scene. Such a contrast to their bravery. It just really is a family event. And it's the best of Boston. It's wonderful to see how people have been responding and how people are pulling together."

The oldest son of former Massachusetts governor Mitt Romney said he was at nearby Fenway Park watching a Red Sox game and got into a cab shortly before the two bombs went off.

"They messed with the wrong people," Romney said. "There's going to be a period of grief, I'm sure there will be some anger. And we're going to want to figure out how to keep this from happening again. Not just here but all over the country."

Romney, who was deeply involved in his father's 2012 presidential campaign, runs an investment firm in Boston.