Two people were critically injured in a house fire in Highland early Monday, officials said.

The incident was first reported as being medical-related around 12:45 a.m., but when San Bernardino County Sheriff’s Department deputies arrived they saw smoke coming from a home in the 7700 block of Chanticleer Road.

Neighbors told responding deputies that there might be people trapped inside and they were able to pull one victim out of the burning house.

Firefighters from Cal Fire San Bernardino then rescued a second victim, Chief Grant Malinowski told KTLA.

Both victims were taken to a hospital in critical condition. Their ages and genders have not been released, but neighbors told KTLA a brother and sister live in the home.

Firefighters battled heavy smoke and fire, and even though the blaze was knocked down, they remained on scene for several hours to make sure the rest of the house was cleared.

The home was damaged in the blaze and has been red tagged.

The cause of the fire is under investigation.