In some of their first public statements since the shooting, which killed 20 children and 6 staff members at Sandy Hook Elementary School, the families of 11 of the victims called for a national dialogue on issues of mental health, school safety and what their nonprofit group, called Sandy Hook Promise, described as “gun responsibility.”

The gathering came as President Obama and Vice President Joseph R. Biden Jr. prepared to unveil gun-control proposals as soon as Tuesday that are expected to call for a ban on the kind of assault weapon and high-capacity ammunition magazines used by Adam Lanza in the Newtown shooting.

But perhaps foreshadowing the difficult and contentious debates to come in Washington, group members declined to offer support for any specific measures, saying they needed time to educate themselves on the issues, and emphasizing that the debate must be broader than gun control.

“It’s only been 30 days, and for the past 30 days we’ve really been looking inward and supporting our community,” said Tim Makris, a founder of the group who had a fourth-grade son at the school, who was not hurt.

“We love the focus of the president,” he added, “and we love that the vice president reached out recently to talk directly to the families that chose to meet with him. But we don’t have an immediate response right now.”

Tom Bittman, another founder, who has children who previously attended the school, said that many of the group members were gun owners.

“We hunt, we target shoot,” he said. “We protect our homes. We’re collectors. We teach our sons and daughters how to use guns safely. We’re not afraid of a national conversation in our community and in Congress about responsibility and accountability. We know there are millions of people in this nation who agree with us.”

The news conference, which included other members of the Newtown community, was the first time a group of Sandy Hook families spoke publicly about the tragedy.

One student critically wounded by gunfire was airlifted to a nearby hospital, Kern County Sheriff Donny Youngblood said.

A second student received minor injuries while falling over a table trying the flee the classroom, and a third student was taken to a hospital complaining of hearing loss from the sound of a gun blast, Youngblood said.

The lone suspect, a 16-year-old male student, was arrested after a teacher and a school administrator who confronted him persuaded the boy to put his gun down, Youngblood told a televised news conference.

His identity was not immediately released, but police said the suspect apparently had a disagreement with the student who was critically injured.