Police have charged a 24-year-old Calgary man in connection with a sex assault on a woman at a bus stop in the city's northwest last week.

The woman was rescued by another bus driver who pulled up to the stop, prompting the attacker to flee.

The suspect surrendered to police without incident on Friday evening after he became aware that investigators were looking for him, police said in a statement.

He is charged with one count of aggravated sexual assault and is scheduled to appear in court on Tuesday.

Investigators believe it was a random attack.

Bus driver comforts victim

The assault happened around 10:45 p.m. last Tuesday as the woman was getting off a bus near the intersection of Sandstone Drive and Berkshire Boulevard N.W.

Officials credited another Calgary bus driver for rescuing the victim. 

Amandeep Hunjan arrived just as the man forced the victim to the ground and attempted to continue the sexual assault, police say. 

Amandeep Hunjan

Bus driver Amandeep Hunjan was pulling into a northwest bus terminal Tuesday night when he interrupted an attempted sexual assault, police say. (Evelyne Asselin/CBC)

"The girl came towards me crying. I asked, 'Do you need any help?' She said yes," Hunjan told CBC News.

He called his dispatcher who called police and an ambulance.

Hunjan brought the woman onto the bus, gave her water and comforted her until police arrived.

She was taken to hospital in stable condition.