Gun rights advocates marshaled one of the biggest crowds to descend on Annapolis for a bill hearing in years Wednesday, packing the halls of the Maryland State House complex to oppose Gov. Martin O’Malley’s plan to institute some of the nation’s strictest gun-control laws.

As they staged a loud protest outside, O’Malley (D) kicked off a Senate hearing that would last more than eight hours, saying the state was compelled to act in the wake of the mass shooting at a school in Newtown, Conn., and urging lawmakers to pass his legislation.

“We choose to take on gun violence this session because every life is precious, every life is needed,” he said. “Is there not something more that we could, and that we should, be doing?”

O’Malley has proposed an assault-weapons ban and new licensing requirements that would require gun purchasers to submit to digital fingerprinting. His bill would also seek to enhance school security and expand the number of categories of mental-health problems that can preclude state residents from owning guns.

Outside the State House, opponents of O’Malley’s plan made it clear that he would be in for a battle. Many adorned their clothing with “Guns Save Lives” stickers and lined up to sign petitions against the bill. Placards bounced to the rhythm of speeches. One woman held up a cardboard sign that said, “When the people fear their government, there is tyranny.”

Kelly Cook, 23, a college student from Arnold, held up a sign that said: “Why do you want to fingerprint me? I am not a criminal.”

“That’s what I want to ask Governor O’Malley,” she said.

More than 700 people on both sides of the issue signed up to testify before the Senate Judicial Proceedings Committee.

Gun rights advocates began their testimony with numerous personal stories. Dozens of Marylanders testified that because of their size, employment, disability or neighborhood they feared life without the protection of a firearm. They said they considered O’Malley’s proposed restrictions burdensome, costly and an infringement of their constitutional right.

More than four hours into the hearing, a Connecticut-based lobbyist for the gun industry drew the most heated reaction from the Democratic-controlled panel.

“The restrictions in this bill are arbitrary. Nothing in it will prevent another Newtown or Columbine,” said Jake McGuigan of the National Shooting Sports Foundation, based in Newtown.

“You’re coming from Newtown, Connecticut, to tell us an assault-weapons ban would not save lives?” asked Sen. Brian E. Frosh (D-Montgomery).

Like others from the gun industry, McGuigan did not back down. He stressed that Connecticut has an assault-weapons ban and that the guns used in the shooting that killed 20 students there were legally owned by the killer’s mother.

With regard to Maryland, McGuigan cited homicide statistics from 2011 that showed just two of nearly 400 killings statewide were committed with rifles that could be banned under O’Malley’s legislation. Outside the hearing, the crowd in an overflow room applauded at the response.

Jeffrey Reh, general counsel for firearm manufacturer Beretta, which has a plant in Accokeek, warned lawmakers that O’Malley’s bill, which outlaws 45 types of weapons and their knockoffs, could have a severe impact on the company’s business. He also said that because gun manufacturers in Maryland are required to register as firearm dealers, it’s unclear whether the company would still be allowed to export guns for sale in other states.

“We’re confronted with a state government that wants to ban the products we make,” Reh said. “Not surprisingly, we are concerned.”

The bill’s advocates were given equal time to testify, and prosecutors, police, academics and mental-health professionals spent hours expanding on how O’Malley’s proposals should reduce the flow of guns to criminals or those who might be a danger to themselves or others.

But most of the day’s debate centered on a broader disagreement over the intent and boundaries of the Second Amendment.

Baltimore County State’s Attorney Scott D. Shellenberger defended O’Malley's proposal.

“We all agree that the First Amendment right, the freedom of speech, is not absolute,” Shellenberger said. “We all agree that you cannot walk into a crowded theater and yell fire. So if we can agree that the First Amendment freedom . . . of speech has reasonable limitations we should be able to find a place where the Second Amendment has reasonable limitations.”

Sen. Nancy Jacobs (R-Harford), the committee’s most outspoken opponent of O’Malley’s plan, said the comparison to gun ownership didn’t work.

“We don’t prevent people from going to the movies in the off chance that they might yell fire,” Jacobs said.

Hope Ingraham of Gaithersburg said she doesn’t own a gun but brought her 9-year-old daughter, Zahira, to the spectacle because she thinks that constitutional rights should not be infringed upon.

“I used to be really anti-gun until [Hurricane] Katrina and I watched all of that Superdome stuff,” she said, “and that’s when I realized — the government lacks the ability to protect us when we need it most.”

After six hours waiting to testify, Athena Andrzejewski of Ellicott City was told that she would not be called before the hearing would be adjourned at 9 p.m.

“I expected a big crowd but not this big,” Andrzejewski said. “I’m glad it’s this big. It means we’re not just going to take whatever comes. It means we are going to fight.”

Kate Havard contributed to this report.