Police investigating a series of student deaths linked to drugs over the weekend have made 10 arrests.
Two 18-year-old women, both students at Newcastle University living in Richardson Road halls of residence, died after taking ketamine, Northumbria Police said.
An 18-year-old man, from Washington in Tyne and Wear, and a 21-year-old Northumbria University undergraduate in Newcastle also died after taking MDMA, the force said.
Northumbria Police said a large-scale investigation is underway, including searching student accommodation with drugs dogs.
The first report was made shortly after 6am on Saturday when an 18-year-old woman was found unresponsive in her student flat. She was believed to have taken ketamine and was pronounced dead at the scene.
An 18-year-old man was arrested on suspicion of supplying a Class B drug and has been released on bail.
The other teenager was found dead in the same halls on Richardson Road at around 1.10pm on Sunday, the force said.
Police said an 18-year-old was arrested in connection with supplying a Class B drug.
Between those deaths, officers were called to an address on the Coach Road Estate in Washington, where an 18-year-old had fallen ill after taking MDMA on Saturday afternoon.
The teen, who was not a student, was pronounced dead shortly afterwards and seven people were arrested.
On Sunday at 8.13am, the force was told that a 21-year-old Northumbria University student had fallen ill at a property in Melbourne Street, Newcastle, after he was thought to have taken MDMA.
He was taken to hospital, but died a short time later.
A 20-year-old man arrested on suspicion of supplying Class A drugs has since been released on police bail.
Police have since carried out a number of consent-based room searches at student accommodation with drugs dogs and more patrols were being carried out on Monday.
Chief Inspector Steve Wykes said: “This weekend we have seen the tragic loss of four young lives and our thoughts continue to be with the family and friends of those who have sadly died.
“Although our investigations are at an early stage and we continue to establish the circumstances around these tragedies, we want to reiterate our warning to people against taking drugs for recreational use.
“The consequences could cost you your life. We will continue to work with both universities and will be increasing our patrols in the areas where these tragedies have occurred.”