Police say a series of robberies that resulted in injuries to several convenience store clerks is shocking and video of one of the incidents has been released in an effort to generate new leads in the case.

Four robberies happened at 7-Eleven and Mac’s stores across the city over the last five months and the offender entered the businesses brandishing a weapon.

In all of the cases, the suspect demanded the clerk to open the till and he then stomps of the heads and necks of the workers before fleeing the scene.

“These are vicious, unprovoked attacks and we are concerned that any further attacks may result in dire consequences,” said Insp. Joe Brar, of the CPS Investigative Operations Section.

The robberies happened at the following locations:

On Monday, July 24, 2017, at approximately 4:25 a.m., at the Mac's Convenience Store, 2905 14 St. S.W.

On Tuesday, Nov. 7, 2017, at approximately 3:30 a.m., at the 7-Eleven, 146-920 36 St. N.E.

On Wednesday, Dec. 6, 2017, at approximately 3:35 a.m., at the Mac's Convenience Store, 2905 14 St. S.W.

On Sunday, Jan. 7, 2018, at approximately 10:50 p.m., at the Mac's Convenience Store, 4100 Marlborough Dr. N.E.

Police have released CCTV footage of one of the attacks and say the victim gave his permission to put out the video to the public in an effort to find the man responsible.

“I think the best way of describing the attack is it’s shocking. This is not something that you see often. When the victim is attacked in these types of incidents, it’s usually when they’re trying to prevent the person from escaping. If you’ve watched the video in this case, you can see that this clerk did nothing to provoke this attack. He was cooperative from the moment this person jumped in. He did everything that we would suggest someone do when they’re faced with a robbery situation, however, it’s incomprehensible why this is happening,” said Brar.

The suspect is described as:

Caucasian male

20 to 35 years old

About 178 to 183 cm or 5’10” to 6’ tall

Slim build

Often described as wearing a black zip-up hooded sweatshirt with the hood up with a scarf or mask covering the lower half of his face and gloves

Anyone with information on the identity of the man is asked to contact the Calgary Police Service at 403-266-1234 or Crime Stoppers through the following methods:

TALK: 1-800-222-8477

TYPE: www.calgarycrimestoppers.org