Police say a fire at a block of flats in Hertfordshire was started deliberately.
Emergency crews were called to Goodes Court in Royston at around 4.40am on Saturday 24 April, following a fire in the communal area.
Two adults and two children were rescued from the third floor - no one was injured.
An investigation has been launched and officers are appealing to anyone who witnessed the incident.
“Thankfully no one was hurt during the incident and the fire service worked quickly to extinguish the blaze; but it could easily have been a very different story", Detective Inspector Mark Corkin said.
“We continue to work alongside the fire service to establish the circumstances around how the fire started. As part of this, we are appealing for anyone with information to please come forward.
"Did you witness any suspicious activity in the area around the time stated? Any information, no matter how seemingly insignificant, could assist us.”