SOUTHLAKE, Texas (CBSDFW.COM) – Sixteen students from Carroll High School are in mandatory quarantine, just one week after starting school.

Carroll ISD says one student tested positive for COVID 19, while the rest came in close contact with the infected student.

Most the exposures occurred at school, but five students are believed to have possibly been exposed during a weekend social gathering, the district said.

With more than a dozen districts across North Texas now offering face to face instruction, schools are trying to quickly contain any cases of COVID-19 to stop the spread.

Fifth graders at Indian Springs Middle School In Keller had only three days of school before the district announced Monday, the entire class of 145 students and their teachers would have to stay home.

The district said three employees working with the fifth graders contracted the virus.

The area’s largest school district, Dallas ISD, has yet to start school.

Dallas ISD begins virtual classes September 8 for at least four weeks.

Even before heading back though, Dallas County estimates more than 200 DISD students tested positive within a two-week period earlier this month.

Nearly half of all infected school-aged children in the county, it found, were high schoolers.