Three men have died and another is in hospital after taking drugs from a suspected dangerous batch of ecstasy.
Suffolk Police were called to reports that a man was found seriously unwell in Rendlesham at 07:10 GMT.
He received treatment at the scene but was pronounced dead.
Later, two other men were reported as unwell at Provan Court, Ipswich. One died at the scene, while the other was taken to hospital in a serious condition.
Police are investigating the deaths and believe they could have been a result of taking ecstasy.
Detectives believe their cases may be linked to another drugs related death on Christmas Eve. A man in his 20s died on Bramford Lane, Ipswich.
Police said all the men were in their 20s.
The tablets are described as red triangles with an "S superman logo" in the middle.
The force has drawn a link between these drugs and dangerous pills with a similar appearance which were in circulation in the Netherlands last month.
Those tablets had a large concentration of PMMA, which acts more slowly than MDMA, the main component of ecstasy. This causes people to take more pills because they think they are not working.
Ch Insp Steve Denham said: "As well as it being illegal to sell and buy drugs, it can also be very dangerous, as we have sadly seen with these tragic deaths.
"If you have been offered drugs in the Ipswich area over the past few weeks, in particular ecstasy, we'd urge you to contact us with any information so that we can find those responsible and remove these dangerous drugs from the streets."