LAWRENCE (CBS) – A Lawrence elementary school was evacuated Thursday morning after the smell of gas was detected, but the city’s mayor said the incident was not related to last months gas explosions in the Merrimack Valley.

An odor was reported at Parthum Elementary School just before 8 a.m. Columbia Gas employees and Lawrence firefighters responded to the scene.

The school was evacuated and students were moved to Lawrence High School temporarily. They were eventually allowed back in their classrooms to finish the school day.

A gas issue caused an evacuation at an Elementary School in Lawrence. (WBZ-TV)

Mayor Dan Rivera said the issue appears to be a rooftop unit and boiler that was leaking gas.

An odor of gas was also reported at the Arlington School, but the issue was caused by a crew purging gas in the building. Air was tested at the Oliver Partnership school and no gas was found. A smell was determined to be from work being performed on the sewer. Neither school was evacuated.

“A heightened sensitivity to the smell of gas. That’s very understandable,” said Columbia Gas president and COO Steve Bryant said. “And we encourage everyone that if you smell gas, you think you smell gas, call us.”

Lawrence was among the Merrimack Valley cities and towns impacted by a series of fires and explosions caused by an over-pressurized gas line last month.