A man found early Saturday morning inside of a Chelsea apartment suffering from serious stab wounds died hours later, police said. Chelsea police officers arrived at 115 Washington Ave. about 1 a.m. Saturday to investigate reports of a possible stabbing, Sergeant Miguel Sanchez said. The victim, who appeared to be in his 20s, was found with stab wounds to his upper torso, Sanchez said. He was taken to Whidden Memorial Hospital in Everett, where he was pronounced dead about 3 a.m., Sanchez said. Investigators did not know Sunday whether the man lived at the Washington Avenue address. His identity was withheld pending notification of relatives, Sanchez said. The Suffolk district attorney’s office is investigating the case as a homicide, Sanchez said.