Reports of a petrol bomb being thrown at a caravan site in Wigan are being treated as arson, police say.
Emergency services were called to the site off Lily Lane in Bamfurlong at 10.30pm on Sunday.
A fire service spokesman said while crews attended, there was no sign of fire when they arrived and no damage to the property.
Police are investigating the incident and officers were at the site on Monday morning.
A police spokesman said: "Shortly before 10.40pm on Sunday, police were called by fire services to reports that a bottle containing accelerants was thrown on Lily Lane, Bamfurlong.
"Emergency services attended the incident.
"No damage or injuries were caused, however the incident is being treated as arson."
Anyone with information is asked to call police on 0161 856 4409 or the independent charity Crimestoppers, anonymously, on 0800 555 111.