A fire broke out inside an apartment in City Heights early Wednesday, which sent a man to a hospital to be treated for life-threatening smoke inhalation, fire officials said.

A resident in the building at the corner of Marlborough and Orange streets smelled smoke about 2:15 a.m., according to the San Diego Fire-Rescue Department. Fire crews arrived, saw smoke coming from the building and knocked down the blaze at 2:32 a.m., fire officials said.

A man who was inside the smoldering apartment was taken to UC San Diego Medical Center to be treated for smoke inhalation, SDFRD spokesman Maurice Luque said.

The fire caused about $50,000 in damage to the property and $25,000 in damage to its contents, according to a SDFRD dispatcher.

The cause of the blaze was under investigation, Luque said.