Police say a social worker in Vermont was killed by a mother upset that she had lost custody of her 9-year-old daughter. The killing of Lara Sobel is the latest in a roster of violent acts directed at social workers. Here's a look at some key facts about violence aimed at social workers:

A DANGEROUS JOB

There have been several high profile attacks against social workers. They include:

— In 2012 in Dade City, Florida, 25-year-old health care case worker Stephanie Ross was stabbed to death by a 53-year-old client.

— A veteran child protective services worker was shot to death in 2005 in Washington state.

— In 2004, Kansas social worker Teri Zenner was fatally attacked with a knife and a chain saw when visiting a client to make sure he was taking his medication.

— In Ohio in 2003, a man was charged with raping a children's service worker.

— In 2001, another Ohio social worker was stabbed to death by a father who had just been told he was going to lose custody of his children.

STATISTICS ON VIOLENCE

The U.S. Bureau of Labor Statistics reported that in 2013, nearly 1,100 social workers — including private and governmental — were injured as a result of violence. Among the 490 state government social workers injured by violence that year, nearly a third worked with children and families.

A 2005 study that interviewed more than 1,000 social workers found 15 percent had been assaulted by a client within the past year, while nearly a third had been assaulted at some point during their career. The National Association of Social Workers said that was the last time a survey like that had been done.

SECURITY

Sobel was killed as she left a state office building. Vermont officials said they are reviewing security at state buildings. They declined to provide specifics but said state workers may see an increased law enforcement and security presence in the coming days.

BEST PRACTICES

Social workers have some ways to reduce the chance of violence in their offices and when making home visits. Besides physical things like never working alone in the office and keeping buildings and grounds well lit, they include:

— Training to recognize when someone is becoming agitated and what do at the first sign that a client is becoming upset.

— Making sure a client's history of violence is known, continually assessing the level of dangerousness and sharing the information with all staff.

— Knowing when and how to try to calm a situation.

— Training in when and how to use non-violent self-defense or to physically escape.

— Leaving a worker's itinerary with office staff, phoning the office frequently when in the field and providing options for staff or police escorts.