Detectives who revisited a house where a man was fatally shot on Saturday afternoon found a second man dead inside the house on Sunday, cops said.

In the initial murder, a 26-year-old man was found shot once in the head in the basement of a house on Erie Avenue near 17th Street around noon Saturday. He was pronounced dead there by medics at 12:15 p.m., police said.

While detectives were in the house investigating that murder on Sunday afternoon, police said, they stumbled upon a second victim. Preliminarily, cops said, that man appears to have been both shot and stabbed. He remained unidentified Sunday, but was estimated to be roughly 35 to 45 years old. He was also pronounced dead inside the house.

Police arrested a suspect in connection with the double murder, but no charges had been filed as of Sunday night.

These two murders bring the weekend homicide tally to seven and the year's murder toll to 307, compared with 303 this time last year.