SAN DIEGO – A brush fire broke out Friday in San Diego’s San Carlos neighborhood, throwing off thick white smoke as firefighters worked to get it under control, officials said.

The blaze was reported shortly after 11:30 a.m. near 7288 Margerum Ave., a San Diego Fire-Rescue incident fact sheet shows. The first units arrived within about five minutes and within 40 minutes, firefighters had it held to about a half-acre in a canyon bordering a nearby road, agency spokeswoman Mónica Muñoz said.

It was reported to be out just before 1 p.m., the agency said in a tweet.

No structures were damaged by the fire and no injuries were reported. Firefighters urge drivers in the area to travel slowly as crews continue to work in the area.

In total, 51 personnel were assigned to the fire, including four engines, three helicopters and two brush rigs, firefighters said. A fire investigator also has been assigned.

It was not immediately clear what sparked the fire.

Check back for updates on this developing story.