California

Alaska Airlines flight makes unplanned landing in California

This photo provided by the Modesto, Calif., Fire Department shows an Alaska Airlines Embraer 175 twin jet after it made an unscheduled landing at the Modesto airport Sunday, April 9, 2017. Authorities said the flight headed from Sacramento to San Diego was forced to make the unexpected landing after a warning light indicated a possible fire in the plane's cargo area. It landed without incident in Modesto on Sunday. (Modesto Fire Department via AP)

This photo provided by the Modesto, Calif., Fire Department shows an Alaska Airlines Embraer 175 twin jet after it made an unscheduled landing at the Modesto airport Sunday, April 9, 2017. Authorities said the flight headed from Sacramento to San Diego was forced to make the unexpected landing after a warning light indicated a possible fire in the plane's cargo area. It landed without incident in Modesto on Sunday. (Modesto Fire Department via AP)  (The Associated Press)

Authorities say an Alaska Airlines flight headed from Sacramento to San Diego was forced to make an unexpected landing after a warning light indicated a possible fire in the plane's cargo area.

Alaska Airlines Flight 3391, which was operated by SkyWest Airlines, landed without incident at Modesto City-County Airport on Sunday.

The Federal Aviation Administration says a cargo fire warning light led the plane to be diverted to Modesto shortly before 7 a.m.

The Modesto Fire Department says firefighters used a thermal imaging camera to examine the cargo area and received a "positive heat signal" but saw no flames. They say the plane's fire extinguishing system had been activated.

SkyWest spokeswoman Marissa Snow says the 55 passengers who were aboard were put on buses and taken back to Sacramento.