The Costilla County Sheriff’s Office has classified the a fire that has grown to more than 40,000 acres in Colorado as “human caused.”

The authorities arrested a Danish man they tied to the start of a destructive fire in Southern Colorado that has grown to more than 40,000 acres and forced hundreds of residents to flee their homes.

The Costilla County Sheriff’s Office classified the blaze, known as the Spring Fire, as “human caused” and said deputies had arrested Jesper Joergensen, 52, on arson charges, it said in a Facebook post on Saturday.

At a meeting with residents on Sunday, however, the authorities clarified that the person they had in custody had not intentionally started the fire. They did not offer further details and sheriff’s officials were not immediately available for additional comment.

In a statement, Immigration and Customs Enforcement said Mr. Joergensen was a resident of Denmark. The agency said it placed an immigration detainer on him on Thursday after his arrest. It was not clear if he had a lawyer.

Jesper Joergensen was…