A fire in a processing machine at the WestRock facility on Merrill Street has been extinguished with no injuries, fire officials said.

The plant makes cardboard boxes for the agriculture industry, said Salinas Deputy Fire Chief Brett Loomis.

Flames were contained to the interior of the building, but smoke was visible from the outside. The building’s sprinkler system held the fire in check until firefighters arrived, and they were able to fully bring the fire under control in about 45 minutes.

Fire officials said the blaze began sometime after 1 p.m.

Twenty six firefighters and three chiefs were on the scene.

Investigators have not determined a cause, but Salinas Battalion Chief Scott Myhre, at the scene, said it was likely caused by heat from a machine and scrap paper.

Myhre said there has been at least one other fire at the plant within the past year.