CONCORD, N.H. — A gun-control group that’s reading the names of thousands of victims of gun violence during a national bus tour apologized for including one of the Boston Marathon bombing suspects on the list.

The Mayors Against Illegal Guns stopped in Concord, N.H., on Tuesday as part of its campaign to build support for legislation to expand background checks for gun buyers. Such legislation failed in the U.S. Senate.

As part of the event, participants read the names of more than 6,000 Americans killed with guns since the December massacre at the Sandy Hook Elementary School in Newtown, Conn. One of the names read June 13 in Concord was Tamerlan Tsarnaev, who died in an exchange of gunfire with police days after the April 15 bombings.

The inclusion of Tsarnaev’s name has outraged victims and relatives of victims of the April 15 bombings, including Pete Brown, of Stoughton, Mass., whose two nephews each lost a leg in the bombings.

“That’s a disgrace,” Brown said Thursday. “I find it offensive someone would include his name. He was promoting violence and his actions resulted in death.”

“To include the name of a terrorist on a list of poor children that were killed by gun violence is sickening,” Brown said.

The gun control group apologized and said it relied on a public list compiled by Slate.com, and that Tsarnaev’s name was on the list.

“He was absolutely not a victim, his name should have been deleted before the list was provided to a family member for reading and his name should never have been read,” the group said in a statement. “It was a mistake, it should not have happened and we sincerely apologize.”

Slate has noted its list is simply an accounting of deaths, not a list of violence victims.

On Thursday, officials confirmed that a New Hampshire lawmaker who was widely criticized for suggesting a federal “black ops” team was behind the marathon bombings had submitted her resignation.

Republican Rep. Stella Tremblay, of Auburn, also had contended that bombing victim Jeff Bauman — who was photographed being wheeled away from the scene and later has both legs amputated — was not in pain or shock. She, too, apologized but is still demanding “a full investigation” of the bombings.

She resigned because she is moving out of her district.