A man has been charged after seven police officers were sprayed with ammonia during an emergency call.
A sergeant was seriously injured during the incident in Ash Grove in Darwen, Lancashire, on Tuesday morning.
Paul Elliot, 46, of no fixed address, is accused of six counts of “throwing corrosive fluid on a person” with intent to burn, maim, disfigure or disable any person or to do some grievous bodily harm to any person.
He is due before magistrates later.
Mr Elliot is also charged with wounding and attempted wounding and is scheduled to appear at Preston Magistrates’ Court.
On Wednesday, the police federation criticised North West Ambulance Service (NWAS) for treating the attack as an urgent, rather than emergency call-out.
NWAS gave the response, at about 02:00 BST on Tuesday, category three status, which means paramedics are expected to arrive within two hours.
Lancashire Police Federation (LPF) said it should have been “at least” category two, which aims for a quicker response.
The sergeant was driven to hospital by colleagues after being told of the possible wait and was treated for serious injuries to his eyes, throat and lungs before being released.
Lancashire Constabulary said he would undergo an operation on his eyes in the coming days.
An NWAS spokesman said the service was “looking into this incident to see if any learning can be obtained and the results will be shared with Lancashire Constabulary”.
LPF chairwoman Rachel Baines said the call officers made for medical help should have been given a higher priority.
“You would like to think if that happened to anybody, regardless of whether they were a police officer, they would at least get a category two response, especially as it wasn’t known what the substance was at that point,” she said.