Attacks on paramedics in Staffordshire have risen fourfold in the past three years according to ambulance chiefs.
Staffordshire Ambulance Service compared the number of reported assaults on staff from April to October each year since 2001.
Spokesman Bob Lee said the reason for the increase was unknown.
In the past two months there have been several aggressive attacks ambulance staff on duty.
They include a paramedic being threatened by two youths armed with knitting needles, another who was threatened with a knife after challenging a man who was searching his ambulance, and a senior nurse whose vehicle was stoned as he travelled to an emergency.
Mr Lee said the service already provides training to teach its workers how to deal with dangerous situations but fears many attacks are not reported at all.
Mr Lee said: "Ambulance staff are disgusted.
"They are almost seeing it as an occupational hazard which is even more worrying. At least once a month they are dealing with a verbal or physical assault.
"We already offer training in various techniques and have a panic system but the fact remains these attacks are unpredicted, unexpected and from unlikely sources."