A woman who alerted police to two young children left in a sealed van for hours may have saved their lives, Abbotsford police said Saturday.

Police said they were doing routine checks at about 1 a.m. PT at the Abbotsford Agrifair when a distressed woman alerted them that two children, ages two and four months, had been left in a van for hours while their father was drinking at the Fat Pig Saloon.

Const. Ian MacDonald said the car was locked, all of the windows were closed and the children were in grave condition.

"They were extremely distressed, as you can imagine. They're still awake and they're in a locked vehicle probably with strange surroundings … they had soiled their diapers and they were extremely dehydrated," he said.

"So even on a summer night — we know we're in the middle of a heat wave here — it was probably still in the upper 20s outside, so you can imagine the heat inside the vehicle."

It was not immediately clear how long the children had been in the van, but one witness said the engine was cold and it was believed they had been left there for several hours.

Both children were taken to a local hospital, where they were deemed to be doing well other than being dehydrated. The children have been placed in the care of the Ministry of Children and Families, police said.

No charges have been laid against the father, 26, an Abbotsford resident.

Police say the children's mother was also out Friday night, but it's unclear whether she and the father were together. Their investigation continues.