Lives could be at risk if people do not stop throwing stones and other items at ambulances, service bosses have said.
North West Ambulance Service (NWAS) has seen three vehicles on emergency calls targeted in March, with one medic being hit in the head through an open window.
Operations director Ged Blezard said the attacks delayed "critical help" and could cause "serious injury or death".
A NWAS spokesman said the "spate" of stone throwing added "a worrying dimension" to what staff already face.
He said NWAS staff had reported more than 730 "physical or verbal assaults" in the past year.
The first incident in March saw a bottle thrown at an ambulance in Stockport on 10 March, which shattered a window and meant the vehicle was taken out of service.
That was followed on 23 March by an emergency medical technician being struck by a stone through the window of a moving ambulance in Liverpool and four days later, stones were thrown at an ambulance in Preston, damaging its windscreen.
Mr Blezard said the attack in Liverpool had left him "absolutely lost for words".
"Had this member of staff been hit harder or in the eye, we could have been dealing with a serious incident and possibly even the death of him, his colleague or the young child we were treating," he said.
He added that the "prospect of missiles coming in through the window" should not be something staff have to worry about and NWAS would work with police to "push for the full extent of the law to be applied to those who think it is amusing to do this".
- 25 March 2019
- 13 December 2018