LYNN - One social worker scans the street before leaving her office, checks the back seat of her car before getting in, and drives around in circles instead of heading straight home to make sure she is not being followed. Another looks for all the exits as soon as he enters a building, in case he needs to run for his life.

"No matter how many safety precautions are in place, bad things can happen," said a Lynn social worker who has had to take children away from gun-wielding adults suspected of child abuse.

This month's fatal stabbing of a Wilmington therapist, allegedly by a client in North Andover, thrust before the public eye the kinds of dangers that hundreds of social workers in Massachusetts encounter daily. They endure threats and physical violence, pay nighttime house calls to crack houses and scenes of recent shootings, usually working for meager paychecks. Some, in their effort to protect abused or neglected children, find themselves confronted by agitated and armed adults.

Angelo McClain, commissioner of the Massachusetts Department of Social Services, recalled the time he went to investigate a report that a family with three children had no running water in their house. The mother thought he had come to take away her children.

"I don't know how that mother got from slamming the front door behind me, to the kitchen, to [being] back in my face with the largest butcher knife I've ever seen in my life," said McClain, who has been threatened on the job dozens of times.

Social workers at the department reported that they had been threatened on the job 343 times during the fiscal year that ended June 30, 2007, said Richard Nangle, a DSS spokesman. In 2006, 19 department workers reported that they had been physically assaulted on the job, and five of those assaults resulted in injuries: for example, when a client punched a social worker in the face in a courtroom, or when someone hit a social worker in the side of the head with a rock while that worker was knocking on a client's door, Nangle said. Some social workers, fearing for their safety, have changed their phone numbers or moved, said Beryl Domingo, who oversees employee safety at the department.

It is not just DSS workers who encounter violence.

Diruhi Mattian, the therapist killed in North Andover on Feb. 6 during a house call to her troubled 19-year-old client, ran a program for mentally ill children and young adults at Family Continuity in Lawrence. That social service agency is funded largely by the state Department of Mental Health and Child and Adolescent Services.

In New York City, a therapist was slashed to death in her office Tuesday night. A man arrested over the weekend and charged with killing her told police he had been looking for another therapist who had institutionalized him 17 years ago.