A small brush fire erupted around noon Sunday at Sky View Lane and The Old Road in Valencia, just East of Six Flags Magic Mountain, spurring an evacuation of the Santa Clarita amusement park and the nearby Hurricane Harbor water park.

Around 12:30 p.m., Six Flags announced on Twitter that guests should evacuate from the park. An hour later, it announced that exit roads had been temporarily closed and that guests would be safe if they stayed on park grounds.

Videos on social media show smoke blowing into the amusement parks as crowds moved to exit. Nine people were transported to the hospital due to smoke inhalation. Flames did not threaten any structures, but both Magic Mountain and Hurricane Harbor closed for the day. Both parks reopened Monday morning.

The Los Angeles County Fire Department said the fire grew to roughly 100 acres and is now 90 percent contained. Firefighters will stay at the scene through the night until the fire is fully subdued.

This was one of at least four brush fires in Los Angeles County that began amid Sunday’s heat wave — the hottest day of the season so far.