Two arson attacks in Derby city centre are believed to be linked, according to police.
One man had to be rescued from the Istanbul Restaurant in the Corn Market after a fire near the main entrance spread through the building.
Earlier, a fire was also started at the nearby Millets store in Morledge.
Both attacks, which happened between midnight and 0050 BST on Friday, are thought to have involved rubbish being set on fire.
A group of four or five people were seen leaving the area after the Morledge fire was started.
They were described as two white men, a black man and a white woman wearing a white top. All are believed to be in their early twenties.
Det Sgt Chris Waters, of Derbyshire Police, said: "We believe that with the proximity of these two fires both in terms of time and location that they are both linked.
"Fortunately, in the second fire at Istanbul, the fire service was able to get it under control and the building was mainly smoke damaged.
"However it could have been a lot worse, especially as a staff member was still in the building on the first floor at the time of the fire."
Anyone who saw people acting suspiciously in the area should contact police.