It was back to school Thursday morning for Northport Middle School students, but not in their usual building.

The middle school on Middleville Road closed Saturday for the rest of the year as the district investigates an odor parents say is making their children sick.

Parents have been calling for the closure of the school for years. Testing by an environmental firm found elevated levels of mercury outside the building.

Eighth grade students will go to the high school, seventh grade students were relocated to East Northport Middle School and sixth grade students are going to Norwood Avenue Elementary School.

MORE: State to probe cancer occurrences in Northport High School’s 2016 graduating class

State Sen. Jim Gaughran says he's hoping to secure funding to help pay for the relocation.

The state Health Department has launched an investigation into health concerns in the Northport-East Northport School district. It was prompted by a group of students who graduated from the high school in 2016 and were all diagnosed with a similar form of cancer.

Parents received a letter from the district superintendent Tuesday, saying the Health Department's probe will focus on the "entire geographical region of the school district."

The letter goes on to say this "did not have any impact" on the decision to close the middle school.

P.W. Grosser Consulting also conducted testing. The group announced its findings at a school board meeting Thursday night.

"In one pool we found 16,000 parts per billion," says Paul Boyce, of P.W. Grosser Consulting. "The other one we found 11,000 parts per billion. The Suffolk County action level is 120 parts per billion.

P.W. Grosser Consulting says it expects to have a full report on the testing completed by March.