The body of a 16-year-old girl discovered in an alley bore signs of being set on fire, police said.
College student Sasha Marsden was found dead in the South Shore area of Blackpool at about 9pm on Thursday.
A man and a woman are being questioned over the death of Sasha, who lived with her parents in the Staining area of the town, and attended Blackpool and the Fylde College. Crime scene investigators are searching the alley behind Kirby Road and a bed-and-breakfast in the same road, which is a few streets from the Promenade.
Officers are also checking CCTV cameras and carrying out house-to-house inquiries.
The two people arrested, a 22-year-old man and a 20-year-old woman, were detained close to the scene in Kirby Road shortly after the body was discovered.