ROANOKE, Va. — Colleagues of the journalists slain a day earlier had a grief-filled return to work here on Thursday, clinging to one another for support and unsure if it was safe to venture out, while Democratic politicians and one victim’s father said the shooting showed the need for tougher gun laws.

“I have watched anchors and reporters half an hour before a newscast be crying in the newsroom and then get on that set and deliver the news,” said Kelly Zuber, news director of WDBJ television, on Thursday, a day after two of its journalists were gunned down. Alison Parker, a reporter, and Adam Ward, a cameraman, were shot Wednesday by a former reporter at the station, Vester Lee Flanagan II, who later took his own life.

“Our meteorologist this morning found a candy wrapper, while on the air, that Adam Ward had always eaten and had left somewhere, and it’s those kinds of little things that are getting to us now,” Ms. Zuber said at a news conference, flanked by dozens of station employees, many of them holding hands. “My sports director just said to me, ‘I lost it when I walked out and saw his car in the parking lot, and had clothes in it.’”

She said that “just as an abundance of caution,” the station did not send news teams into the field for live reports after the shooting on Wednesday, or on Thursday. “Law enforcement has actually reached out to us and said hey, if you’re doing a live shot, let us know, we’ll be there and we’ll help you,” Ms. Zuber said.

Ms. Parker’s father, Andy Parker, made a series of emotional appeals for laws that would prevent mentally ill people from buying guns.

“I’m going to do something, whatever it takes, to get gun legislation, to shame people, to shame legislators into doing something about closing loopholes and background checks,” Mr. Parker said Wednesday night on Fox News. “This is not the last you’ve heard of me. This is something that is Alison’s legacy that I want to make happen.”

Thursday morning, on CNN, he said, “I’m for the Second Amendment, but there has to be a way to force politicians who are cowards in the pockets of the N.R.A. to make sensible laws to make sure crazy people can’t get guns.”

The National Rifle Association did not respond to requests for comment on Thursday.

Appearing with Mr. Parker on Fox, Chris Hurst, Ms. Parker’s boyfriend and a fellow reporter at WDBJ, spoke more indirectly, emphasizing that he had covered mental health issues and did not want society to react to the tragedy by deciding to “discriminate against everybody else who has a mental illness.”

“Clearly, something went wrong here between him leaving our station and being able to purchase a gun and commit a premeditated act,” Mr. Hurst said, speculating about Mr. Flanagan. Even before the shooting on Wednesday morning, he said “there had been ample time beforehand where many, many other things went wrong. Those need to be addressed.”

After the shooting, Gov. Terry McAuliffe, a Democrat, and Hillary Rodham Clinton joined President Obama in renewing their previous calls for new controls on gun purchases, like a more comprehensive background check system.

But Republicans pushed back.

“It’s not the guns, it’s the people who are committing these crimes,” said Senator Marco Rubio of Florida, a Republican presidential contender, at a campaign stop in New Hampshire. “What law in the world could have prevented him from killing them?”

Mr. Flanagan, 41, who went by the name Bryce Williams in recent years, had not been convicted of a crime or adjudicated mentally ill, so he apparently passed a background check in June, when he bought the Glock 19 handgun used in the killings. Federal officials said he bought it legally from a licensed dealer.

He was described at multiple former workplaces as difficult, combative, even threatening, yet none of that came to light when WDBJ, a CBS affiliate, looked into hiring him, said Jeffrey A. Marks, the station’s president and general manager.

“Our H.R. team followed up on references, a variety of sources, and they all came back positive,” he said, referring to the human resources department. “It’s very hard to get a negative reference these days.”

When asked what the station might have done differently, Mr. Marks said, “We can probably screen more,” but then backed away from that position, saying, “I don’t know the answer to that question, nor do I think I’m likely to come up with it in the first day after a disaster.”

Mr. Flanagan worked for less than a year at WDBJ before being fired in February 2013. He filed a discrimination complaint and a lawsuit against the station, claiming that as a black man, he was discriminated against, and subjected to racist comments.

“I am absolutely certain that nothing like that happened in this case, and that it was in the imagination, and perhaps in the preconception and the preplanned attitudes, of the fellow in this case,” Mr. Marks said.

Mr. Flanagan was disciplined “for failure to check his facts in a news story, and generally for poor news judgment,” Mr. Marks said. “Vester’s behavior annoyed a lot of people in the newsroom, not just photographers — producers, other reporters, anchors and managers.”

He confirmed, as was revealed in court papers, that Mr. Flanagan’s bosses ordered him to use the services of his workplace’s employee assistance program, because of “behavior, the anger, and the inability to work with his colleagues.” When asked if Mr. Flanagan got some kind of help at that time, Mr. Marks said, “He complied with what we asked him to do,” but did not elaborate.

On WDBJ on Thursday morning, Kimberly McBroom, an anchor, said, “We come to you this morning with very heavy hearts,” before she and her colleagues observed a moment of silence for Mr. Ward and Ms. Parker.

The moment of silence came at 6:45 a.m., the time a day earlier when Ms. Parker and Mr. Ward were killed.

Ms. McBroom joined hands with a weather forecaster, Leo Hirsbrunner, and an anchor, Steve Grant, who was from a sister station in Missouri. “Joining hands here on the desk,” Ms. McBroom said, her voice faltering at times. “It’s the only way to do it.”

She was also the anchor when the shootings occurred, while Ms. Parker and Mr. Ward were interviewing Vicki Gardner, a local Chamber of Commerce official during a live report. When the report was interrupted by the sounds of gunshots and screams, and jumbled images from the camera falling to the floor, the broadcast cut back to the stunned face of Ms. McBroom, who told viewers she was not sure what had just happened.

“I thought maybe it was fireworks, or something that blew on his camera, or maybe someone was shooting far away,” she said in an interview on Thursday. “All those things were going through my mind — not this.”

“The longer we went without hearing from them, the more I worried something bad had happened to them,” she added.

Ms. Gardner was wounded in the attack and had emergency surgery. Her husband, Tim Gardner, told CNN on Thursday morning that a bullet had grazed her spine. She was in good condition but was expected to have additional surgery, he said.

Mr. Gardner said that he had watched the shooting as it happened — “I was rather surprised, stunned” — and was able to talk to his wife while on the way to the hospital. She told him she had been shot in the back, he said, but was able to walk to the ambulance.

“My wife happened to be there at the wrong time,” he said.