St. Paul's Hospital in Saskatoon has been closed to visitors until further notice, as officials try to stop the spread of a gastro-intestinal virus that resembles the Norwalk virus.

The outbreak was first noticed on Friday and two units of the hospital were made off-limits to visitors.

It was hoped the spread of the virus would be contained, however, on Tuesday additional cases were found.

While the hospital has yet to positively identify the Norwalk virus, the symptoms exhibited are consistent with that condition.

Patients and staff have fallen ill with vomiting and diarrhea among their chief symptoms.

According to officials 27 patients, or about one in ten of those currently in the hospital, have exhibited some of the signs of the virus.

Because of that, officials said they were taking the extraordinary measure of closing the hospital to visitors in an effort to contain the outbreak.

Jean Morrison, president of St. Paul's Hospital in Saskatoon, says the facility is now off-limits to visitors due to concerns about a Norwalk-like virus. (CBC)

"It's out in the community and it's coming into the hospital," Jean Morrison, president of the hospital, said Tuesday. "And once it comes, we have people in such close confines that it's very easy to transmit from one person to the next."

Officials said no one should visit the facility but added people with scheduled appointments for day surgeries or procedures may keep their appointments, but they will be kept to their care area.

St. Paul's Hospital is one of three in Saskatoon.

The emergency department will remain open, although the health region was advising people to go to E.R. only for true emergencies.

According to the health region, the virus behind the outbreak can strike very quickly and people may not even be aware they are contagious until they have symptoms.

People were also being reminded to use good hygiene techniques.

Morrison added the restriction on visitors will be in place for at least the next four days.