Calgary police are investigating after they say a female real estate agent was sexually assaulted by an unknown male during an open house in the southeast.

Officials say the realtor was working at an open house in the 800 block of McKenzie Drive S.E. at about 2 p.m. on Saturday when she was approached by a man.

The man began to speak with her and despite her attempts to end the conversation, the man would not leave.

At that point, police say he grabbed her and sexually assaulted her.

The woman managed to break free and convinced him to leave, but the suspect returned a short time later.

The realtor locked the door before he could get back into the house and called for help.

The man left and returned again a third time, but fled again before police arrived.

Police searched the neighbourhood but could not find the man.

The suspect is described as:

Middle Eastern or South Asian descent

Salt and pepper beard

Medium build

Short, brown hair

He was wearing a grey shirt and dark shoes at the time of the incident.

The Calgary Real Estate Board's CEO Alan Tennant says the incident is "very concerning."

"We take REALTOR® safety very seriously and have shared the content of the CPS release with the membership," he said in a statement to CTV News.

Anyone with information on this incident or the identity of the man is asked to contact police by calling the non-emergency number at 403-266-1234 or Crime Stoppers anonymously through either of the following methods:

TALK: 1-800-222-8477

TYPE: www.calgarycrimestoppers.org