Police have issued a warning after a man in his 30s died and a man in his 20s is seriously unwell after consuming unknown substances.
The investigation is at an early stage but Police believe that drugs may be a factor in both incidents.
A number of other people are also believed to have sought medical treatment last night after becoming unwell.
Detectives want to hear from anyone who was at the property on Northland Road in Moneymore in Derry last night where the incidents happened.
They're advising anyone considering taking any type of substance not to do so.