PORTLAND, Ore. (KOIN) — Crews were called out to a vegetation fire in Oregon City Friday evening, said Clackamas Fire.

A hayfield on S Criteser Road had caught fire and was roughly 3/4 of an acre in size when firefighters arrived.

In a 6:30 p.m. update, Clackamas Fire said the blaze had grown to around six acres before it was extinguished. Firefighters reported seeing two-to-three-foot flames in the field. Water tenders were brought out to the scene since there were no nearby fire hydrants.

Clackamas Fire said there were people working in the field at the time the fire broke out, and no injuries have been reported.

The cause of the fire is unknown at this time.

This is a developing story.