A man has been arrested after two children were critically injured in a house fire.
A three-year-old girl and a boy, aged five, remained in hospital after a blaze in Coronation Crescent, Preston, at about 20:00 BST on Friday.
Their mother, thought to be in her 20s, is also in hospital with injuries that are not life-threatening, police said.
A 24-year-old man was arrested on suspicion of arson with intent to endanger life.
A fourth person was also treated for injuries at the scene.
Lancashire Police said they attended after receiving "reports of a fire with several people trapped inside the house".
Det Ch Insp Graham Hill said: "We are aware of rumours circulating online about an explosion having occurred and we would like to clarify that this is not the case."
The arrested man was from the town and he remains in custody.
The force said a joint investigation was under way with Lancashire Fire and Rescue Service to try to confirm the cause of the fire.
Officers have appealed for anyone with information to contact police.