Police have arrested a 26-year-old man in connection with a double stabbing Monday night of a toddler and the boy's 43-year-old grandmother inside the woman's West Philadelphia home.

The suspect's name was not released pending the completion of charges. He was expected to be charged with aggravated assault, resisting arrest and related offenses, police said Tuesday.

Lt. John Walker of the Southwest Detective Division said the suspect is the grandmother's boyfriend and sometimes stays in the rowhouse on the 700 block of North Preston Street.

The woman and her boyfriend — who were both under the influence of drugs or alcohol — had been arguing with each other, then began shoving each other, Walker said. The boyfriend then stabbed the toddler in the head, then stabbed the woman, Walker said.

Officers who responded to the home at about 7:30 p.m. Monday after calls to 911 found the woman outside with a knife blade protruding from her back left shoulder. She told police the person who stabbed her was on her porch, police said. 

After the suspect ran into the woman's house, officers pursued him upstairs. Walker said the man tried to jump out of a third-floor window. As he attempted to flee, he broke through the window and cut himself in his right arm and hand, police said.

While inside the house, police found the woman's 2-year-old grandson in the second-floor hallway area, bleeding from a cut to the back of his head, police said. The boy was immediately taken by police to the Children's Hospital of Philadelphia in critical condition.

The woman was taken to Penn Presbyterian Medical Center Monday in critical condition and her boyfriend, who was in custody, was taken to Penn Presbyterian in stable condition. Walker said both victims and the suspect were in stable condition Tuesday.