A man renting a room in a San Marcos home was arrested Sunday on suspicion of setting the house ablaze and killing two people whose bodies were found on the second floor of the burning structure, officials said.

The man, 33-year-old Luis Alvarado, was detained at the scene and later was arrested on two counts of murder and arson and booked into the central jail, where he’s being held without bail, sheriff’s officials said. Alvarado also was charged with resisting arrest.

The fire was reported around 11:45 p.m. at a home on Lacebark Street near Borden Road. By time deputies and firefighters arrived, the home was fully engulfed in flames.

Firefighters discovered the two people inside a second-floor room and fire officials requested the sheriff’s bomb-arson investigators conduct an investigation into the cause and origin of the fire. Homicide detectives also responded.

Homicide Lt. Juan Marquez said Alvarado was a tenant who had been renting a room in the home. The names of the two people found dead inside the house have not been released.

The  Medical Examiner’s Office will determine the identity of the individuals and the cause and manner of their deaths, Marquez said.

Anyone with information about the incident is asked to call sheriff’s investigators at 858-285‑6330 or 858-868‑3200 if calling after hours. Anonymous tips can be left at Crime Stoppers at 888-580‑8477.