Police in Sheffield are appealing for information about four suspicious fires.
Emergency services were called to Kimberley Street at 12.30am on June 25 after an HGV driver who was sleeping in his cab woke up and discovered his vehicle was on fire.
A wheelie bin was found against the vehicle.
A short time later at 1.15am another HGV was discovered on fire on Greenland Road, Darnall.
The driver was again asleep inside the cab and was notified by nearby workmen that the truck was alight.
Both drivers were uninjured.
At around 2am patio furniture outside a pub on Handsworth Road and a detached garage on Clifton Crescent were found to be on fire.
Officers, supported by the police helicopter, searched the area.
A joint investigation with the fire service is ongoing but it is believed the fires were started deliberately and may be linked.