The simpleton solution government usually chooses is to prohibit ownership or possession of some item used in violence. It never works, because such bans usually affect only law-abiding people. Those who commit violence also don't have any qualms about breaking the law, so the ban does not affect them.

Here are some solutions that do not rely on banning things to reduce the amount of violence:

BIGGER SENTENCES Increasing the sentence for any violent crime will reduce the probability of violent events
MORE POLICE Stop paying for the arts and sports, and hire enough police to do the job.
LESS TYRANNY Remove picky laws that control what people have or do on their own property. These laws make people mad at the elitists who want them. This includes all zoning.
LOWER TAXES High taxes keep people from paying their bills, and often cause their jobs to disappear. Taxes also cause property seizures. This causes anger.
CRACK DOWN ON GANGS Gang violence must be eliminated. Law enforcement must arrest the leaders for what they order others to do, and keep them in jail for decades.
HIGHER PENALTIES FOR WEAPON USED IN CRIME Don't penalize anyone for having a gun. Penalize those who use weapons while committing other crimes. Such criminals should go to prison for decades.
DON'T LEGALIZE DRUGS A few people might be mad because drugs are illegal, but drugs do cause violence. Hard drugs are responsible for violent attacks. Others commit violence because they are in agony from drug withdrawal. And marijuana use, while not making people more violent, can make people more careless with weapons. Two pot users decided to fight out a pistol duel over who got the last joint. The survivor said he didn't think anyone would get hurt.
KEEP TRAFFIC MOVING Road rage is a major cause of violence. Traffic blockages are a major cause of road rage. Keep traffic flowing freely, and you get rid of road rage. But too many governments concentrate on stopping traffic, rather than moving it.
It's time to stop favoring creditors over debtors when people have lost their jobs. Since government overspending caused the job losses, government should be required to pay the creditors of its victims.
MAKE JOBS MORE PERMANENT Many of the workplace violence events are caused by an employee suddenly losing his job. He then starts shooting up the workplace. Employers should have to pay higher unemployment fees for each discharged employee.
PROHIBIT POLITICAL DISCRIMINATION Prohibit discrimination against any person because of political belief. Only political and religious groups may discriminate in hiring due to the political beliefs of a job applicant or employee.
GOVERNMENT MUST NOT VIOLATE ANY RELIGION It is wrong for government to do anything that violates any religion. The fact that government thinks it is important to do the thing does not justify the fact that government is doing something that alienates members of any religion. Some people (e.g. Tim McVeigh) are driven to violent action to put an end to the violations.
SECURITY GUARDS There is nothing like a security guard to deter violent activity before it starts. In addition, a security guard can notify the authorities when violence occurs.
VIDEO SURVEILLANCE In places where violence is likely to erupt, video cameras monitored by trained people or police can be used to summon authorities fast. It should not be done in homes or apartment houses, but businesses wanting to participate should not have to pay for police monitoring if they want it
PANIC ALARM In places where violence is likely to erupt, provide a panic alarm system to alert authorities. This could be a set of buttons or devices like fire alarm stations. There could be also be hidden buttons only trained people know how to use.
PING-PONG-BALL TRAP The ping-pong-ball trap is a locked bulletproof room placed below critical locations, such as entrance airlocks, bank teller windows, and other critical locations. The room is filled with ping-pong balls to a depth that will cushion someone's fall, and completely envelop that person afterward. A trap door can be activated to drop a violent person into the room, and then locks to keep that person in the room.
GUN MAGNET A powerful magnet is mounted where a gunman or terrorist would have to pass through. A security guard, principal, or other trained person can then activate it just as the perpetrator passes it. It attracts anything made of iron or steel and makes it stick to the wall. The perpetrator can't aim the weapon, and probably can't fire it.
PERP GLUE Jets hidden in the walls spray the intruder with a gluey substance than not only holds the intruder in place, but restricts movement of his limbs, and causes any gun to blow its breech if fired. The cops have the glue removal solvent.
GAS THE PLACE Inject sleeping gas into any place where violence is occurring. Once everyone is asleep, send in the cops with breathing devices. The cops can then disarm the perpetrators. They wake up in jail. This would be a useful in a hostage situation.
LOCK THE AIRLOCK Once a fleeing robber or a suspicious person enters the airlock between two sets of doors, lock all the doors. Since the entire airlock is bulletproof, he can't get out or shoot his way out. Lock the outside doors first, so unsuspecting people don't get trapped with the perp.
SMARBLES Release thousands of slippery marbles on the floor, so a fleeing crook slips and falls, and then can't stand up. The perp will probably lose his weapon when he falls.
SMART GUN The ideal smart gun knows when it is being held by a person not authorized to use it, and knows when it has been taken away from where it is supposed to be. As soon as either is true, it locks the trigger and broadcasts a GPS signal to cops.
CRAZY BUILDING Activating this device causes lights and other devices to turn on and off rapidly and randomly, as though there has been a major failure. This totally confuses the perpetrator.
FAKE DISASTER NEWSCAST Activating this broadcasts fake radio warnings of an impending disaster (nuclear attack, broken dam, etc). Any perp who is not bent on self-destruction will stop his attack and get out of there as fast as he can. Start it with the tones used for weather alerts.
VISUAL OVERLOAD Bombard the perp with very bright flashing lights of various colors. This so overloads his visual system that he can't think. But do not use lights that are so bright that they cause permanent damage to either the perpetrator or bystanders.
AURAL OVERLOAD Bombard the perp with a very confusing jumble of sounds and tones. This so overloads his aural system that he can't think. But do not use sounds so loud that they cause permanent damage to either the perpetrator or bystanders. Also note that very low frequency sounds can painfully damage the hearing of some people, while other people are unaware of them. So avoid very low frequencies.
HOT OR COLD RUNNING AIR If the perp is holed up in a room in a building, and the air temperature wiring can be accessed without exposing a technician to danger, make the room unbearably hot or unbearably cold.
DRENCH THE PERP Use fire hoses to blast the perp with torrents of water.