Police have condemned five attacks on officers in Newcastle over the weekend and say that such behaviour is " completely unacceptable".
"Policing has always been about making communities safer and protecting the public. Unfortunately officers can occasionally be assaulted while carrying out these duties.
"Thankfully serious attacks like those which took place over the weekend aren't common place, and a number of suspects were quickly arrested - however this sort of behaviour is completely unacceptable.
"I have personally visited all the injured officers and they are all receiving the best medical treatment.
"Every officer undergoes a high level of self defence training and carries certain protective equipment but as a force we take any assaults on officers and staff extremely seriously and will take robust action against anyone responsible."
A police officer is in hospital tonight after he and two of his colleagues had the chemical ammonia thrown over them in Newcastle. In a separate incident in South Shields, an officer was knocked unconscious as she tried to make an arrest.
Northumbria Police says it's a disgrace that officers are attacked while protecting the public. Watch Julia Barthram's report.
Policing can be a dangerous job, according to Detective Superintendent Steve Howes from Northumbria Police. He spoke to ITV Tyne Tees as fellow-officer was detained in hospital with burns to his eye, after an incident involving ammonia.