LEWISTON — Three more students at Bates College tested positive for COVID-19 this week, part of a surge of new cases in Maine.

The new tests show there are four active cases among the more than 1,700 students at the college, all of them in isolation housing to help thwart further spread of the coronavirus.

Joshua McIntosh, dean of students, said in a message Friday to the Bates community that after contact tracing Thursday evening, it does not appear the new cases are related to each other, “meaning that there does not appear to be a common source for the transmission.”

College officials said Friday that the lack of a common source indicates a need to be even more vigilant than Bates has been, particularly in light of a growing number of infections in Maine in recent days.

Until this week, the college had largely avoided any problems, with a total of three student cases on campus this semester, two of them near the start of school in late August and early September.

The three new positive tests were among 824 tests done Tuesday, according to the Bates COVID-19 dashboard and several college officials.

The director of Maine’s public health center, Dr. Nirav Shah, said on Twitter on Friday that the state has 103 new COVID-19 cases, its highest total.

“The surge is here,” Shah said. “Take action now. For your sake, and for the sake of your family and community, wear a mask and stay apart. This is serious.”

McIntosh told students in a message earlier in the week that requests to relax “some of our public health practices and to restore elements of the pre-pandemic student experience” can’t be done.

“As much as all of us would like to do so, this is not possible for the foreseeable future, given the trends at work in this country and the state of Maine with the spread of COVID-19,” he said.

He said students who don’t want to cope with the rules during a Maine winter, when outdoor gatherings are difficult, can request a leave of absence for the semester that begins in January. They also have the option of studying remotely.