Philadelphia Police say a stepfather beat and sexually assaulted a boy who died a short time later.

Officers responded to a home on S. Conestoga Street near Woodland Avenue in Southwest Philadelphia after receiving a 911 call Wednesday evening from a 24-year-old man who later turned out to be the suspect, police said.

Officers went upstairs to find the boy on the floor without a pulse, police said.

The boy, who would have turned 2 next month, was found with bruises and scratches on his body and appeared to have been choked, police sources told NBC10’s Denise Nakano.

Medics rushed the boy to the Children's Hospital of Philadelphia where doctors pronounced him dead a short time later. "The attending physician noted multiple bruises on the child and signs of sexual assault," police said in a news release.

Police took in the suspect, who calls himself the boy's stepfather, in for questioning, police said.

Police said they plan to charge the yet-to-identified suspect with attempted murder, aggravated assault, rape, child endangerment and related offense.

The medical examiner would need to complete an autopsy and release the results before the suspect could face homicide charges, police said.

Correction: Sources initially said police went to the home to serve a warrant but later clarified that a 911 call led them to the unresponsive boy.