​RCMP are looking for two teenage suspects who fled in a stolen truck after allegedly seriously assaulting a female staff member at the Elk Island Youth Ranch on Saturday night.

Police say two boys — aged 14 and 15 and both residents of the ranch — assaulted the woman with a weapon inside a building just after 11 p.m. They then fled in a stolen truck.

RCMP were called at 1:15 a.m., about two hours after the woman was assaulted. The woman, who is in her 60s, was seriously injured and taken to hospital in Edmonton by STARS air ambulance.

"It did take some time before staff at the ranch learned that the assault had taken place. She just wasn't found right away," Cpl. Mike McCreedy said.

"She is still at the hospital and we're still waiting for further details as to what the doctor's prognosis is and exactly what trauma she received."

It did take some time before staff at the ranch learned that the assault had taken place. She just wasn't found right away. - Cpl. Mike McCreedy, RCMP

The woman is expected to survive, McCreedy said.

The two suspects have been identified by staff, but cannot be named under the Youth Criminal Justice Act. Both boys are previously known to police.

The 14-year-old boy is described as white, with black hair and is around five-foot-two and 106 lbs.

The 15-year-old boy is also described as white, and is five-foot-five and 121 lbs.

McCreedy could not say how long the boys had been living on the ranch.

The stolen truck in which they fled is described as a run-down, grey two-door 2000 Chevrolet Silverado with the Alberta licence plate BFJ 5597.

Police say the truck is distinct in that it has a new driver's side door.

"It's a truck that belongs to the youth ranch. It's not something they would have had access to. It is a vehicle that the staff use on the ranch," McCreedy said.

'We're exploring all avenues'

It's not known where the suspects may have gone, but RCMP are warning the public not to approach the boys or the stolen vehicle. It's not known what weapon was used during the assault, or if the boys still have it on them.

McCreedy said he doesn't believe a firearm was used during the assault.

STARS spokesperson Fatima Khawaja confirmed the woman suffered a "traumatic injury," but could not confirm whether the injury was caused by a knife.

RCMP say the suspects fled in this truck. (Supplied/RCMP)

Anyone with information about this incident is asked to contact Fort Saskatchewan RCMP.

"We're exploring all avenues," McCreedy said.

"Likely they're not still in the area, but we're conducting patrols in and around Lamont and Elk Island area, and just covering all bases, really."

The Elk Island Child and Youth Ranch is an intensive treatment program for children and youth aged 10 and older covered under the Child, Youth and Family Enhancement Act.

The ranch has five live-in facilities, which are located just east of Lamont, Alta.