The province's police watchdog says there are no reasonable grounds to charge two officers involved in the fatal shooting of a 37-year-old man who killed his pregnant wife and wounded his two young sons in a stabbing incident in East Gwillimbury in February.

The attack occurred on Feb. 6 at a home on Ridge Gate Crescent in Mount Albert.

In a report released Saturday, the Special Investigations Unit (SIU) said York Regional Police officers received a series of 911 calls about a stabbing at the residence at around 2:25 p.m. that day.

When officers arrived on scene, they found one injured woman lying in the driveway of the home and a 38-year-old pregnant woman was found dead on the front porch.

The SIU said two police officers forced their way into the home and found a man armed with a knife holding a two-year-old child, who had sustained a severe knife wound. According to the SIU, the man assaulted the child before going into a bedroom and stabbing his four-year-old son.

The two officers then fired multiple shots at the suspect, ultimately killing him.

The children were rushed to hospital for treatment and both survived the attack.

"The officers exercised significant restraint before resorting, reasonably, in my view, to lethal force," SIU Director Joseph Martino said in his report.

"(Subject Officer #1), though aware of the devastation the complainant had just wrought upon his wife and sister, attempted to talk him down even as the complainant threatened and then assaulted his 2-year-old son by smashing his head against a hallway wall."

The report notes that the officers held their fire until the suspect attacked his four-year-old son.

"Given every reason to believe that the complainant might take another stab at his children at any moment, causing grievous bodily harm or death, (Subject Officer #2) resorted to the only force capable of being immediately incapacitating, namely, his firearm," the report read.

"In so doing, it is not a stretch to say that the officer’s actions might well have saved the lives of one or both of the kids."

The SIU is an arm's-length provincial agency which investigates anytime police are involved in a death, serious injury, or allegations of sexual assault in Ontario.