A brush fire was burning out of control off the 15 Freeway in the Cajon Pass, prompting the freeway's closure.

A San Bernardino City Fire Department spokesman said 100 acres have burned so far and homes are threatened.

The fire broke out after 11 a.m. near Kenwood Avenue in Devore.

The cause of the blaze was not known, and it's unclear when the 15 Freeway would reopen.

The area is seeing high temperatures and dry conditions.

Scores of firefighters were on the scene.