LEWISTON, Maine — The head of the federal Bureau of Alcohol, Tobacco, Firearms and Explosives says he fears that a drumbeat of mass shootings and other gun violence across the United States could make Americans numb to the bloodshed, fostering apathy to finding solutions rather than galvanizing communities to act.

Director Steve Dettelbach’s comments to The Associated Press came after he met this past week with family members of some of the 18 people killed in October at a bowling alley and a bar in Lewiston, Maine by a U.S. Army reservist who later took his own life.

He said people must not accept that gun violence is a prevalent part of American life.

“It seems to me that things that we used to sort of consider memorable, life-altering, shocking events that you might think about and talk about for months or years to come now are happening with seeming frequency that makes it so that we sort of think, “That’s just the one that happened this week,’” he said. “If we come to sort of accept that, that’s a huge hurdle in addressing the problem.”

Dettelbach, whose agency is responsible for enforcing the nation’s gun laws, met for nearly two hours at Central Maine Community College with relatives of those killed and survivors of the Lewiston shooting. An AP reporter also attended, along other with law enforcement officials.

Some expressed frustration about missed red flags and questioned why the gunman was able to get the weapon he used. Dettelbach told his audience that they can be a powerful catalyst for change.

“I’m sorry that we have to be in a place where we have to have these horrible tragedies happen for people to pay attention, but they have to pay attention,” Dettelbach said. “I can go around and talk, but your voices are very important and powerful voices. So if you choose to use them, you should understand that it makes a difference. It really makes a difference.”

Those who met with Dettelbach included members of Maine’s close-knit community of deaf and hard of hearing people, which lost four people in the Oct. 25 shooting at a bowling alley and at a bar.

Megan Vozzella, whose husband, Stephen, was killed, told Dettelbach through an ASL interpreter that the shooting underscores the need for law enforcement to improve communications with members of the deaf community. She said they felt out of the loop after the shooting.

“Nothing we do at this point will bring back my husband and the other victims,” Vozzella said in an interview after the meeting. “It hurts my heart to talk about this and so learning more every day about this, my only hope is that this can improve for the future.”

There are questions about why neither local law enforcement nor the military intervened to take away weapons from the shooter, Robert Card, despite his deteriorating mental health. In police body cam video released to the media this month, Card told New York troopers before his hospitalization last summer that fellow soldiers were worried about him because he was “gonna friggin’ do something.”

Dettelbach, in the AP interview, declined to comment on the specifics of Card’s case, which an independent commission in Maine is investigating. But he said it is clear that the nation needs to make it harder for people “that everyone agrees should not have firearms, who the law says are not entitled to have firearms, to get them because it’s too easy to get them now.”

Dettelbach’s conversation with victims was part of a tour in New England that also included meetings with law enforcement and others to discuss ways to tackle gun violence. Dettelbach, who has expressed support for universal background checks and banning so-called assault weapons, said he regularly meets with those affected by gun violence.

“Each one of these shootings is a tragedy that takes lives and changes other lives forever. And that’s whether it makes the news or not, whether it’s the suicide of a child or a drive by in the city, whether it’s a massacre at a parade, a spray bullets on a subway, whether it’s a man who kills his family, murders police” or a student with a rifle “shooting up their school,” he said during a speech at Dartmouth College on Wednesday.

“I submit to you that it is our patriotic duty as Americans to respond, to think of these people, to have their backs, to view this tough news as a call to action.”