A man could "potentially lose his sight" after a substance was thrown in his face in a St Helens street.
At around 9.20pm, the man was stood by his car on Milton Street, Sutton Manor when two men in bubble jackets threw a substance in his face .
He suffered breathing difficulties and extreme irritation to his eyes and he has been taken to hospital where he was treated.
Early indications from medical staff are that the victim could potentially lose his sight.
The offenders are described as being in their mid 20s and white.
They were both wearing bubble jackets and were last seen heading towards Jubitts Lane.
An investigation is underway and house-to-house enquiries are being carried out in the local area.
Detectives will also be examining CCTV footage in a bid to identify the offenders.
Detective Inspector Lisa Ryan said: “This was an unprovoked attack and enquiries are ongoing to establish the full circumstances in relation to the incident.
"The investigation is in the very early stages and we are working to determine what was thrown at the victim.
“I would appeal to anyone who was in the area of Milton Street who may have witnessed the incident, or two men in bubble jackets acting suspiciously in the area before or after the incident.”