Riverhead firefighters responded to an alarm for a structure fire at a Roanoke Avenue farm at about 11:45 a.m. Thursday.

Straw stored inside a hoop house on the site was on fire, according to Riverhead police. The fire sent up a large plume of smoke that was visible from as far away as the L.I. Expressway.

Firefighters were able to quickly douse the smoky fire despite muddy conditions that made accessing the site difficult. They were released from the scene after about an hour.

No one was injured in the incident. The Riverhead Town fire marshal’s office is investigating the cause of the fire.