Police investigating the drug-related deaths of four young people, including three university students in Newcastle, have arrested 10 people, the Northumbria force said.The investigation began following the deaths of two 18-year-old women and two men, aged 18 and 21, who were all found unresponsive at addresses over the weekend.Northumbria Police said it received the first report at 6.05am on Saturday of an 18-year-old woman, who was a student at Newcastle University, found unresponsive at a