A 50-passenger regional jet landed safely Sunday night after the pilot experienced some fuel-related issue on board and called for a cautionary emergency response, a jetport spokesman said.

Commute Air flight 3991 landed safely at 8:42 p.m. after arriving in Maine from Chicago’s O’Hare International Airport, said Zachary Sunquist, a spokesman for the Portland International Jetport.

Sundquist did not know the precise nature of the fuel issue, but said firefighters returned to their firehouses after the uneventful landing.