LOS ANGELES (CBSLA) – Thirteen California State University, Northridge students who traveled to a large conference in Washington, D.C., last week have self-quarantined after at least three conference attendees — including one from L.A. County — tested positive for the novel coronavirus.

The students will be self-isolated for a period of 14 days, CSUN President Dianne Harrison said in an open letter to the campus Monday.

READ MORE: Son Arrested For Murder Of Mother Found Dead In Mission Viejo Home

U.S. Vice President Mike Pence speaks during the American Israel Public Affairs Committee (AIPAC) 2020 Policy Conference in Washington, DC, on March 2, 2020. (Getty Images)

The 13 students have shown no symptoms at this time.

Although Harrison did not specify the conference in question, it is believed to be the American Israel Public Affairs Committee (AIPAC). More than 18,000 people attended the conference, which included speakers such as Vice President Mike Pence and Sen. Cory Booker.

On March 6, the D.C. Department of Health confirmed that two people who had traveled to AIPAC from New York had tested positive for COVID-19.

On March 7, the Los Angeles County Department of Public Health confirmed that an L.A. County resident tested positive for COVID-19 after returning from AIPAC. That patient is a parent at Harkham Hillel Hebrew Academy in Beverly Hills, a Jewish day school. The school will be closed through at least Thursday.

On Sunday, California State University, Long Beach reported that 10 of its students and two advisers who also attended AIPAC were self-quarantined as well.

According to the U.S. Centers for Disease Control and Prevention, COVID-19 is spread from person-to-person through close contact, usually within 6 feet, and mainly via respiratory droplets when an infected person coughs or sneezes.

MORE NEWS: Marsh Homers Off Kopech In 8th, Angels Top White Sox 3-2

Symptoms include fever, cough and shortness of breath. People are likely most contagious when they are most symptomatic. Coronavirus can also be spread by touching contaminated surfaces and then touching your mouth, nose and eyes.