Update: Thursday, July 2, 2009 at 10:00 a.m.

A brush fire burned 75 acres in Castaic Wednesday afternoon off the I-5 near Templin Highway.

One lane of northbound traffic is still closed and crews remain in the area in an effort to control the fire, which is still burning, but has been contained at 75 acres.

UPDATE: Both directions of the I-5 are now open; however one lane remains closed on the northbound I-5 at Templin Highway.

Shortly after 5 p.m. Wednesday, the Los Angeles County Fire Department and the California Highway Patrol originally forced the closure of all lanes of the Northbound I-5 at Parker Road and all southbound lanes at Highway 138. Lanes were closed for nearly two hours.

It was determined that all of the burn area was within the Angeles National Forest. ANF spokesperson Dee Dechert told KHTS that one firefighter suffered heat exhaustion, but that there were no other injuries. No structures, commercial buildings or autos were burned and no evacuations were carried out.

“We have investigators on scene and we are not confirming nor denying any rumors as to the cause of this fire,” Dechert said. “We are hoping to have the fire controlled before winds kick up this afternoon.”

Agencies who worked on the fire included ANF, Los Angeles County Fire, Los Angeles County Sheriff’s Department, California Highway Patrol, Ventura County Fire and Caltrans. Dechert said that at one point, more than 350 personnel were working on the fire, including 9 crews, 15 engines, 2 dozers and 10 air units: 6 helicopters and 4 air tankers.