12/17/2011 02:46 EST | Updated 05/09/2013 07:14 EDT

Ex-boyfriend Saw Victims In Store Before Alberta Highway Shooting

Derek Jensen, the 21-year-old ex-boyfriend of Tabitha Stepple, was also driving north on Highway 2, apparently looking for Stepple, when he found her and three friends in the 7-Eleven store in Claresholm, Alta., shortly before shooting them and taking his own life, police say.

RCMP released the details leading up to the shooting early Thursday morning along the dark highway in a news release Saturday.

While there was no confrontation at the store, RCMP say minutes after leaving, Jensen rammed the rear end of the vehicle being driven by Shayna Conway, Stepple's friend from work, roughly 1.5 kilometres north of Claresholm, around 3 a.m. MT

Conway stopped the SUV she was driving and got out. It is not known at this time if she was aware who had collided with her. Jensen exited his Pontiac Sunfire as well and shot Conway numerous times with a Heckler & Koch nine-millimetre hand gun, police said.

Jensen then walked up to the vehicle, which still contained Conway's boyfriend, Tanner Craswell, as well as Stepple and Mitchell MacLean. Jensen fired numerous rounds into the car, murdering Craswell and Stepple where they sat.

Although MacLean was also shot, he got out of the vehicle and was later found by police in the east ditch of the highway, a short distance from the SUV.

He was transported by ground ambulance to the Claresholm Hospital where he was later transported via STARS air ambulance to Foothills Medical Centre in Calgary. MacLean succumbed to his injuries before he arrived.

After shooting these four people, Jensen turned his firearm on himself while still at the scene and committed suicide. Two other firearms were located in his vehicle when searched by police: a loaded 12-gauge shotgun and a loaded Winchester rifle.

Conway was the sole survivor in the shooting and is expected to recover.