WESTPORT — Officials warn that recent “substantial transmission” of COVID-19 in the community is cause for concern.

Over the last two weeks, a rise in the number of COVID cases in Westport means the town is now in the state’s “red” category — the most serious status, with a transmission rate of 15 or more per 100,000. As of Thursday, according to state data, Westport was the only town in southwestern Connecticut assigned the red classification.

“There has been an increase of COVID cases in Westport putting the community into a higher category of COVID transmission,” Mark Cooper, executive director of the Westport-Weston Health District, said in a Friday statement.

“High-risk individuals should take extra precautions, particularly those who are unvaccinated, by avoiding large gatherings. Getting fully vaccinated, wearing masks and social distancing continue to be strongly recommended for all,” Cooper added.

The townwide alert comes in the aftermath of reports last week there had been a sudden rise in the number of COVID cases at Saugatuck Elementary School. That prompted state and local health officials to recommend that SES students and staff be tested regularly for the virus.

The school district’s COVID-19 dashboard, as of Friday, reported that 26 people systemwide (students and staff) had confirmed positive COVID-19 cases and are isolating, and 55 people are currently in quarantine.

Meanwhile, the Friday announcement from First Selectman Jim Marpe’s office underscored that local executive orders requiring mask wearing indoors remain in force.

Those mandates require that everyone entering all municipal buildings and public spaces, such as stores, restaurants, museums and businesses, wear a mask regardless of vaccination status.

An exemption to Westport’s indoor mask mandate has been granted for gyms and other workout facilities.