The fire was reported shortly after 5 a.m. Monday in a small house in Austin, where the seven victims apparently were asleep, the local TV channel ABC13 quoted fire department officials as reporting.
Two girls, aged 9 and 15, were in critical condition, Austin- Travis County Emergency Medical Services spokesman Eric Jakubauskas was quoted as saying.
Three adults also had serious injuries.
All the victims, whose names were not immediately release, were transported to hospitals, according to the report.
Officials said they were trying to determine if the victims were related.
The cause of the fire was under investigation.