The Littleton Fire Department is responding to a gas leak Friday morning on Cedar Road, officials said.
Residents in the immediate area have been evacuated, said Kim Fleck, a spokeswoman for the department. Firefighters were called to the scene at about 9:45 a.m., Fleck said.
Crews from National Grid are working to shut off the gas, the department said on Twitter.
One of the possibilities they are looking into is that the gas line was unproperly marked, Fleck said.
Mina Corpuz can be reached at mina.corpuz@globe.com. Follow her on Twitter @mlcorpuz.