Ontario’s police watchdog says it has interviewed several witnesses in connection with a grisly incident in East Gwillimbury over the weekend that left two people dead and three others injured, including two small children.

York Regional Police were called to a home on Ridge Gate Crescent for a weapons call at around 2:30 p.m. on Feb. 6.

Officers arrived to find a 38-year-old woman dead at the front of the home. After going inside, they became involved in an interaction with a man in the home. Two officers discharged their firearms and the 37-year-old man was struck. He was pronounced dead at the scene.

A 35-year-old woman, a four-year-old boy and a two-year-old boy were taken to hospital to be treated for serious injuries.

In a news release on Monday, the special investigations unit said they interviewed a witness officer yesterday but that the two subject officers in the case have not yet been interviewed. The statement pointed out that subject officers are not legally obligated to speak with the SIU but may do so if they wish.

The SIU also reported Monday that three civilian witnesses were located and interviewed and video footage was retrieved from two sources.

Investigators are also now in possession of cartridge cases and projectiles seized from the scene, as well as use-of-force equipment, including firearms, from the two subject officers. A knife was also recovered from the scene.

The SIU said that at the request of the deceased man's family, they will not be releasing his name.

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.

Investigators are asking anyone with further information to get in touch with the SIU.