CALGARY -- Alberta Health Services says norovirus was the likely cause of an outbreak of illness linked to a chain of Calgary shawarma restaurants.

An investigation was launched Dec. 6 after reports of diners becoming sick after eating at Jerusalem Shawarma. Reports were received from 17 different groups who said they ate at multiple locations between Dec. 4 and Dec. 12.

"Between Dec. 7 and Dec. 18, AHS completed 27 inspections at all Jerusalem Shawarma locations," reads a statement from AHS.

"Following these inspections, no closure orders were issued as it was determined that norovirus was the likely cause of the outbreak and public health inspectors discarded potential foods of concern (i.e. cut vegetables, sauces, etc.), implemented enhanced handwashing procedures and increased disinfection levels and frequencies."

AHS is continuing to work with the restaurants to ensure the outbreak is contained.

The illnesses were linked to four locations:

722 85th Street S.W.

8650 112th Avenue N.W.

5255 Richmond Road S.W.

301 16th Avenue N.W.

AHS says 123 people became sick. Anyone with questions or concerns is asked to contact Health Link to speak with a registered nurse, 24-hours a day, by calling 811.

"As always, Albertans are reminded to stay home when sick, refrain from preparing foods while sick with diarrhea or vomiting, and always wash hands well with soap and warm water before preparing foods or drinks or before eating or drinking," reads the statement.

"Handwashing is vital to preventing the spread of illness in the community and at home. A chlorine-based disinfectant (i.e. 1/3 cup regular bleach to 4 litres of water) is an inexpensive way to disinfect any contaminated and/or frequently touched surface if anyone is experiencing vomiting and diarrhea at home."