Thousands of Koreans are now under quarantine after an outbreak of the deadly Middle East Respiratory Syndrome (MERS) virus, and officials are scrambling to get a handle on the problem.

Even those who don’t have the virus are now being locked into hospitals where the virus is believed to be in order to stop its spread, with two hospitals currently under a two-week lockdown preventing anyone from entering or leaving, according to a Reuters report.

A total of 162 have been infected of MERS in South Korea, and 20 people have died. It’s the largest outbreak of the virus outside of Saudi Arabia, and all of the infections are belived to have happened in health care facilities.

A total of 6,500 people are in quarantine so far, and most are inside their own homes — including a village of 105 people that authorities have entirely closed off from the outside world.

According to the Centers for Disease Control and Prevention, MERS is a viral respiratory illness that has an unknown source, although officials believe that it originates from animals and possibly camels.

MERS symptoms include fever, coughing, and shortness of breath. It can also result in gastrointestinal symptoms, such as vomiting, nausea, and diarrhea. The disease can result in even worse complications that can lead to death, including pneumonia and kidney failure. Around 30-40 percent of people who get MERS eventually die from it, although most of them had an underlying medical condition to begin with. Those with preexisting medical conditions are more likely to get the illness.