Images released this morning show blood smeared on the walls inches away from the entrance of the property, which has been cordoned off after the 11-month-old boy and a woman in her 30s were knifed.
Police are hunting 25-year-old Rehan Khan.
The house is on the Oriel Estate in Hanworth, Feltham, west London, which was on lockdown after the horror incident last night.
The baby remains in a critical condition, but the woman is understood to be stable with non life-threatening injuries.
Both were rushed to west London hospital by air ambulance for treatment.
Cops are now hunting for a man known to live at the address, who is believed to know the victims.
Witnesses said a police helicopter was spotted flying overhead as well.
A Metropolitan Police spokesman said: “At the scene a woman and an infant had suffered stab wounds.
“Both victims were taken to a west London hospital where their conditions are serious but stable at this time.
“We await further updates. A crime scene has been established and officers remain at the scene.”