Orono firefighters responded to Hasbrouck Court after a contractor hit an underground gas line and 18 tenants were evacuated Wednesday afternoon.

A natural gas leak in downtown Orono on Wednesday resulted in the evacuation of about 18 tenants from a Mill Street apartment building and the closure of two downtown streets.

Orono firefighters responded to the Hasbrouck Court apartment building after a contractor hit an underground gas line while digging.

“The leak happened when they actually hit the line when they were digging around the area of gas line,” said Capt. Kevin Siros of the Orono Fire Department.

Orono schools — located within a mile of the gas leak — canceled outdoor activities and brought students indoors for recess, according to an email to parents from Superintendent Meredith Higgins. Mill Street and Pine Street were shut down as authorities investigated the leak and reopened within an hour.

After firefighters evacuated residents from the apartments they checked the building and surrounding area for natural gas, Siros said. Since natural gas is lighter than air, a light breeze carried it away.

Bangor Natural Gas crews arrived on the scene soon after to deal with the leaking pipeline.

“They were able to clamp the line and allow occupants to go back to their apartments,” Siros said.

Tenants were allowed back into the building at about 12:35 p.m, and Orono schools resumed outdoor activities before 12:50 p.m.

“According to law enforcement, there was no danger in the immediate vicinity of our schools, but out of an abundance of caution, we decided this was the best course of action,” Higgins said in an email to parents. “We just wanted to let you know what occurred and assure you that all is well here.”

The University of Maine also sent out an alert informing students and staff to avoid the streets that were shut down, and then another alert when the roads reopened.