The main and emergency entrances to Northampton General Hospital are shut because a man was sprayed with an unknown substance while in his car, it has been confirmed.
Northamptonshire Police believe he has been treated and discharged, and are continuing to investigate the circumstances of the attack.
A police statement read: "Emergency services are dealing with an incident following an assault on a man in the Ecton Brook area of Northampton earlier today, where he was sprayed with unknown substance while in his car.
"The man experienced irritation to his nose and attended Northampton General Hospital for treatment.
"As a precaution, police and fire placed a cordon around the vehicle in the hospital car park while an investigation takes place.
"The hospital main entrance and emergency department entrance remain closed and patients and visitors to the hospital are asked to use other entrances."