POUGHKEEPSIE, N.Y. — Two colleges north of New York City were holding classes remotely, suspending in-person activities and barring visitors Monday after detecting multiple cases of the coronavirus.

Iona College in Westchester County said it was moving classes online for two weeks starting Monday after identifying 58 cases. The 4,000-student Catholic college said in an online posting that the uptick was among some athletic teams and that the virus was transmitted through a "single, isolated event." 

Marist College in Poughkeepsie announced its initial lockdown Thursday after learning of coronavrius cases stemming from a weekend off-campus gathering held without masks or social distancing. The college did not specify the number of positive cases and on Sunday, extended the lockdown restrictions until Tuesday.

The college of more than 6,000 students said it was conducting multiple rounds of targeted coronavirus testing for students and had instituted "a precautionary temporary quarantine" at its Fulton Townhouses.

"While our success in managing this situation in the first six weeks of the semester is a testament to our work together, this recent turn of events serves as a critical reminder: COVID-19 is still a threat to the campus and the larger community, and must be taken seriously," college administrators said in a web post. 

A growing number of colleges have switched to remote classes or tightened rules in recent weeks to try to slow the spread of the virus.