A chief fire officer has hit out after crews were barricaded in an area and pelted with petrol bombs.
Chris Lowther, chief fire officer at Tyne and Wear Fire and Rescue Service (TWFRS), said the incident was "some of the worst attacks I've known in my 26 year career".
In a tweet, he said the attack, which happened in West Denton, Newcastle, on Saturday, could not "go unanswered".
The sentiment was echoed by the Fire Brigades Union, which said it was "premeditated violence designed to seriously cause harm to firefighters" and needed to be "condemned by all parts of the community and stopped".
Lowther tweeted: "Last night, @Tyne_Wear_FRS crews from West Denton suffered some of the worst attacks I’ve known in my 26 year career.
"They were barricaded in an area where a car was deliberately set on fire and had petrol bombs thrown at them. Petrol bombs. This escalation can’t go unanswered."
TWFRS told the BBC that crews were called to a car fire which turned out to be a pile of rubbish set alight.
It said nobody was injured and crews had followed protocol to withdraw and call the police.
The people responsible were reportedly wearing masks, making it hard to identify them.
Sharing its chief fire officer's tweet, TWFRS wrote: "A strong message here from@TWFRS_CFO.
"These are mothers, fathers, sons, daughters, brothers and sisters behind the uniform. And they do what they do to keep you safe. Those responsible don’t care but we know many of you do. If you know those responsible contact the police."
The Fire Brigades Union's branch that represents members in the North East, said the incident was "absolutely disgraceful".
It tweeted: "Absolutely disgraceful, this is not ASB, this is premeditated violence designed to seriously cause harm to firefighters.
"This needs to be condemned by all parts of the community and stopped."