Authorities say they arrested four people on suspicion of murder in Nipomo on Sunday in connection with the discovery of a charred body at the scene of a grass fire early in the morning east of Santa Margarita.

Firefighters found the charred remains shortly after 5 a.m. off Parkhill Road, in a remote area south of Highway 58 and about six miles east of Santa Margarita, said Rob Bryn, spokesman for the county Sheriff’s Department.

A series of arrests took place through the day, starting at a mobile home park in Nipomo, authorities said.

Sheriff’s Department and county District Attorney’s Office investigators arrested Jason Adam Greenwell, 20, Frank Jacob York, 19 and Rhonda Maye Wisto, 47, all of Nipomo.

They also arrested Ty Michael Hill, 28, of Santa Maria, the Sheriff’s Department reported.

All four were booked into County Jail on suspicion of murder, according to the Sheriff’s Department.

No information was available on their bail.

There is no word on when the identity of the deceased will be learned.

Bryn said it might require checking DNA or dental records.

Bryn said that when Cal Fire arrived at the grass fire shortly after 5 a.m., firefighters soon realized it appeared to be arson, with a suspicious death involved.

He said homicide investigators, coroner deputies, a crime-scene investigation team and the CHP’s Multidisciplinary Accident Investigation Team — which has sophisticated Global Positioning System equipment for detailed mapping of crime scenes — were at the scene through the day Sunday.

Investigators remained until dusk and then secured the scene, Bryn said.

The investigation is expected to resume this morning, he added.

Investigators also remained through the night at a home in Nipomo, according to the Sheriff’s Department.

Bryn said 10 members of the county Sheriff’s Search and Rescue Unit, with a police dog, also did a perimeter search of the area. And other teams of deputies and detectives pursued leads.