Sussex Police are investigating four fires over three days during which cash was stolen.
The most recent incident took place at 1.30pm on Tuesday (August 28).
West Sussex Fire & Rescue and Sussex Police attended reports of a fire in a store cupboard located on Comet Ward on the Sixth Floor at Crawley Hospital.
Emergency contingency plans were implemented by hospital staff and emergency services and all patients and visitors were safely evacuated.
The fire was extinguished by WSFRS and at this time the cause is subject of a joint agency investigation by fire investigators and West Sussex CID.
No one was injured or required medical treatment as a result of the fire.
During the fire a small quantity of cash was stolen from the till in the hospital restaurant.
The first arson took place at 2pm on Sunday (August 26) at The Royal Albion Hotel, Old Steine, Brighton, the second fire began shortly after 12 noon on Monday (August 27) at the Brighton Museum and Art Gallery and the third fire, also on Monday occurred at The Sealife Centre, Brighton at around 4.30pm.
Fire alarms were activated and the buildings were evacuated on all three occasions. The fires were small, caused minimal damage and were extinguished by staff prior to the arrival of the fire brigade on all three occasions.
When staff returned to the buildings, having been given the all clear by East Sussex Fire and Rescue, it was discovered that money had been taken from tills left unattended.
A Sussex Police spokesman said; “Damage was very limited and there were no injuries, but detectives at Brighton and Crawley are actively investigating examining the circumstances of each incident and are pursuing joint lines of enquiry, but are currently keeping an open mind as to whether there are definite links between them.”
Anyone with information about the Brighton incidents should contact Sussex Police on 101 quoting serial 0953 of 26/08.
Anyone with information about the Crawley fire should contact the same number quoting serial 0949 of 28/8.
You can also call independent charity Crimestoppers anonymously on 0800 555 111.