Six “suspicious” fires that sparked inside Golden Gate Park over the course of just 24 hours prompted officials to boost police presence in the park.

All fires, ranging from tiny blazes up to one that burned an acre, were in an isolated area near the Polo Field and the angling and casting ponds, between Metson Road and Martin Luther King Jr. Drive.

None of the fires threatened nearby residential and commercial neighborhoods, and no injuries were reported, according to the San Francisco Fire Department.

“San Francisco fire investigators (are) investigating (the) Golden Gate Park fires as suspicious,” San Francisco fire Lt. Jonathan Baxter said in a statement.

Two blazes broke out near the Polo Field on Friday afternoon, when the larger fire burned 1 acre, officials said. Both blazes were contained before 7 p.m.

On Saturday morning, joggers lingered on the trail overlooking the scene where blackened branches twisted up from black soil. A single sprinkler in the middle of the debris showered water in a circular motion on surrounding dead branches and shrubs located between the Polo Field and the fly-casting pools.

Some passersby, such as Elliott Lane of San Francisco, braved the rotating sprinkler and climbed to the base of the blackened earth, burned leaves crunching beneath his shoes with every step. He snapped some photos behind a charred tree.

“I live a mile away and heard about the fires from my roommate, so I came here to check it out,” Lane said.

Yellow caution tape circled a fire scene near the angling and casting ponds, where a bike frame and lottery tickets were found among scattered papers. It is unclear if that area cordoned off by tape is a separate scene or connected to the roughly 1-acre blaze beside the trail.

More than a dozen people lined the nearby ponds and cast their lines into the blue pools, despite the thick wildfire smoke swept in from the Camp Fire that blanketed the sky.

Park rangers and police officers from Richmond Station will patrol the area where the blazes originated, park officials said.

Fire officials are coordinating the investigation with the San Francisco Police Department and the San Francisco Recreation and Park Department.

Anyone with information about the fires may call the San Francisco Fire Department at 415-920-2933 or email firepio@sfgov.org. Callers may remain anonymous.

Fire officials advise parkgoers to call 911 if they see anything suspicious.

Lauren Hernández is a San Francisco Chronicle staff writer. Email: lauren.hernandez@sfchronicle.com Twitter: @LaurenPorFavor