Putnam — Two young children were found dead on the third floor of a Prospect Street multifamily home Tuesday after an early-morning fire engulfed the home, state police said.

The 3-year-old and 6-month-old children’s bodies were taken to the state medical examiner’s office, state police said in a news release. State police fire and explosion detectives, along with Eastern District Major Crime Detectives, are working with the Putnam fire marshal to determine the cause and origin of the 12:39 a.m. blaze.

When firefighters responded to a 911 call about a fire at 6-8 Prospect St., they found the home fully engulfed in flames, state police said. Four people were taken to the hospital with injuries that were not life-threatening, police said. The children were discovered early Tuesday afternoon, police said, and pronounced dead at the scene. Their deaths will be investigated by major crimes detectives.

The home also will be examined by state fire marshals for possible code violations. The structure sustained heavy damage, police said, and the investigation is ongoing.