A timeline of emergency response on the day Lisa Gibson drowned her children in a bathtub, and then herself in a river, shows a long delay until Winnipeg police found the kids and requested an ambulance.

According to police, the detailed timeline began at 7:58 a.m. on July 24, 2013, with a 911 call from a woman giving the address to the family's home in the city's Westwood area.

Police response

Emergency vehicles swarmed the area of Coleridge Park Drive in Westwood, around the Gibson home, on the morning of July 24. (John Redekop/CBC)

The first officers arrived at the home at 8:06 a.m., but it wasn't until 8:32 a.m. that the officers advised a dispatcher that a two-year-old and a baby were found in the tub and were not breathing.

Eight seconds later, the dispatcher forwarded a request to the Winnipeg Fire Paramedic Service to rush an ambulance to the home.

The children — Anna, 2, and Nicholas, three months — had no vital signs and were rushed to hospital, where they were pronounced dead.

Police searched for Gibson for four days until the 32-year-old's body was recovered from the Red River on July 27.

The cause of death in all three cases was determined to be drowning. The children's deaths were ruled as homicides, while Gibson's death was deemed a suicide.

'There was a delay,' police chief admits

"Yes, there was a delay, and certainly we should have found the children," police Chief Devon Clunis admitted to the Winnipeg Free Press in a video that the Winnipeg Police Service posted on YouTube on Thursday.

"They conducted a search of the premise, didn't locate anyone inside the premise, and then they started to do a search outside of the home," Clunis explained.

"It was 26 minutes later that the grandmother initially discovered the children."

When asked if the 26-minute delay was critical, Clunis pointed to what Manitoba's chief medical examiner revealed in his review of the Gibson case.

"There is nothing from the ME's report that could indicate that any actions by the WPS played any part in the ultimate tragic outcome," he said.

The deaths have cast a spotlight on the issue of postpartum mental health issues, including depression. Police have said postpartum health issues were part of their investigation.

Last month, Dr. Thambirajah Balachandra ruled that a full inquest is not necessary in the deaths of Gibson and her children.

Instead, Balachandra recommended that the College of Physicians and Surgeons of Manitoba "investigate the diagnosis, treatment, and management of Gibson and take adequate action to educate the medical community to prevent similar tragedies in the future."

Response timeline released by police on Dec. 5, 2013

SOURCE: Winnipeg Police Service