Four girls became seriously ill while attending a wedding celebration on the Paul First Nation, west of Edmonton, early Sunday morning and were taken to hospital after allegedly taking what they thought was ecstasy.

Police were called after the girls suddenly became sick. Three of the teens were rushed to hospital in Edmonton, RCMP spokesperson Cpl. Wayne Oakes said.

Two girls remained in critical condition. The third girl is showing signs of improvement, police said late Monday afternoon.

A fourth girl was assessed and released at the scene Sunday morning.

"It's hard. It's hard to see those children suffering like that in the hospital, and they're just, like, unconscious. It's sad," said Dennis Paul, a media spokesperson for the Paul First Nation.

"Oh my God … you just want to go home and hug your children."

Oakes would not confirm if drugs contributed to the girls' illness but said police were looking at all factors and consulting with medical staff.

"We will have to look at everything, consider everything and overlook nothing," he said.

Investigators are trying to speak with anyone who may have had contact with the girls before and after they got ill in order to determine what made them sick and whether there is any risk to others, police said.

A crisis unit has been assigned to provide counselling to the girls' classmates, Paul said. On Monday afternoon, Alberta Health released a written statement on behalf of the families of the three girls.

"The families at this time are not prepared to make comments on the physical condition of the girls as they are still waiting upon results pending more tests and medical evaluations," the statement said.

"The families have voiced concerns about how these young ladies were able to obtain such a dangerous substance in a supposedly safe environment."

In the statement, the families also passed on their thanks to the medical staff at the Stollery Children's Hospital, as well as thanks to their family, friends and community " for the outpouring of support, compassion and continued prayers."