"We have to be careful not to overreact to one incident or another," he said. "They tried bans like this before, and they were not effective."
O'Malley's licensure plan would apply to all firearms besides rifles and shotguns, an exception designed for hunters and sportsmen. The extra scrutiny is aimed as a deterrent to so-called straw purchases, gun buys made on behalf of people who do not want to be linked to the weapon.
"Someone asks you to purchase a handgun for them, and you know they're going to use it in a crime, and you have to go the state police to get fingerprinted — you're certainly not going to do it," said Vincent DeMarco, an Annapolis gun-control lobbyist and national coordinator of Faiths United to Prevent Gun Violence.
Gun-control advocates said that while assault weapons can kill more efficiently, most gun deaths are linked to handguns. In Baltimore last year, according to police, handguns were used in all but three of 183 gun-related killings.
A spokesman for Mayor Stephanie Rawlings-Blake and Police Commissioner Anthony W. Batts said the administration supports the concept of stricter licensing as a deterrent to straw purchases.
"It is one of the ways that firearms get into the hands of people who wouldn't otherwise be allowed to have them," said Jim Green, the Police Department's government relations director.
Public safety experts skeptical of the deterrent effect of a handgun licensing still welcomed the proposal as an investigative tool for gun-related crimes. "It's just like the way surveillance cameras on the street does not deter crime," said Leonard Hamm, a former city police commissioner who teaches a public safety course at Coppin State University. "What the information does is point us in the right direction."
O'Malley's proposals are likely to be considered alongside novel ideas pushed by gun-control advocates who see increased public willingness to tighten gun regulations.
One plan would require Maryland gun owners to buy liability insurance similar to the requirement for cars. The proposal by Montgomery County state Sen. Jamie Raskin is designed to harness market forces to keep guns out of the hands of dangerous people the same way the cost of car insurance can keep bad drivers off the road. Baltimore Del. Jon Cardin has proposed a bullet tax and $25 gun registration fee, cash that would go to improving mental health services.
O'Malley vowed to ban the sale of "military assault weapons that have no place on our streets" and to limit the size of gun magazines to prevent mass shootings. Maryland already limits magazines to 20 bullets, and gun-control advocates hope to halve that.
O'Malley also said he wants to standardize school safeguards across the state, which vary widely. He plans to create a state center for school safety and devote funds from the capital budget to make school buildings safer, including installing cameras at entrances, having doors that lock automatically and buzzer entrance systems.
While O'Malley also announced plans to focus resources on providing early intervention for those with serious mental health issues, his remarks to the gun summit centered on controlling the sale of the most lethal weapons. The state's assault weapons ban would not take legally owned guns out of homes, an aide said, but it would prohibit buying or possessing them in the future.
"We know that it makes absolutely no sense, when you look at the level of carnage on our streets from guns, to blame every factor but guns," O'Malley said.
Baltimore Sun reporter Michael Dresser and Reuters contributed to this article.