A 14-year-old boy was found dead on a street in Holbeach in the early hours on Saturday morning, police confirmed.
He was found dead at the scene on Fleet Street in the town.
His family have been informed, police said.
A 15-year-old girl and two 19-year-old men were arrested on suspicion of drug related offences and have been released on bail.
The police investigation into the circumstances is ongoing.