A 42-year-old Red Deer school bus driver faces impaired and dangerous driving charges after a bus hit a tree Monday afternoon.

A witness called 911 after the school bus carrying 18 public school students aged five to 12 ran over the tree and a road sign in the Vanier Woods neighbourhood, Red Deer RCMP said in a news release Tuesday.

The crash occurred about 4 p.m. Officers opened an impaired-driving investigation at the scene and continued the investigation into the evening, RCMP said.

The school bus struck a tree and a speed limit sign Monday afternoon in Red Deer's Vanier neighbourhood. (Amanda Patton) The Red Deer Public Schools expressed shock and anger at the situation.

"Adults who serve our students carry a significant responsibility for their safety and care," said Stu Henry, superintendent of schools. "It is devastating when an adult betrays the trust we have with our students and parents."

The school district confirmed no students were injured in the incident and acknowledged that parents are upset.

"Parents are appropriately concerned," said Bruce Buruma, the director of community relations with Red Deer Public Schools.

"It was a stupid decision by the bus driver and they're reacting to that. .. and we expect that."

Amanda Patton's 11-year-old son Marco was on the bus.

"I'm outraged, I'm concerned," Patton told CBC News Tuesday.

Patton heard sirens from her house Monday and drove to the area where she saw several police vehicles.

"Are the kids ok?' That was the first thing out of my mouth." she said, adding that the police told her the children were fine.

She still didn't know what was happening but noticed what the police were doing.

"They had a bag … like a gym-style bag," she recalled. "They had her water bottle out, and I actually watched them smell this water bottle and I thought, 'No, there's just no way that what I'm thinking is happening — can't possibly be happening.' "

Shelly Kolodychuk, 42, is charged with impaired operation and dangerous operation of a motor vehicle, operate motor vehicle over 80mg and fail to remain at scene of collision. Patton's son told her at one point, the bus was driving on the wrong side of the road.

"I had to drive him to school this morning because he doesn't want to go on the bus again," Patton said. "It's pretty scary as a parent to realize that we've placed so much trust in somebody who assumes this responsibility as a bus driver."

The driver is an employee of Prairie Bus Lines, the company contracted to transport students in the district.

The company issued a statement Tuesday saying they have a zero-tolerance policy on drugs and alcohol and a process to test employees suspected of being under the influence of drugs or alcohol.

"In this case, there were no visible signs of impairment prior to the driver's afternoon departure," the statement read.

The company said they have taken "the appropriate action to ensure our 'Safely Home' commitment is upheld."

Shelly Joy Kolodychuk of Red Deer is charged with impaired driving, driving with a blood-alcohol level over 80 milligrams, dangerous driving and failing to remain at scene of a collision.

She is scheduled to appear in Red Deer provincial court on July 12.