The Austin Statesman-American reported there were about 20 people on the poolside wooden structure when it collapsed during a birthday party about 7:30 p.m. Saturday.
Austin Fire Department spokesman Palmer Buck said six of the victims were taken to medical facilities for treatment, with four of them reported to have serious but non-life threatening injuries, the newspaper said.
The cause of the collapse had not been determined.
The deck surrounded an above-ground pool and was attached to the back of a house overlooking a ravine, the newspaper said. People on the deck when it gave way fell 18 feet into the ravine and slid another 20 feet down the steep hillside, officials said. Some of the party-goers were partially buried in the debris and Buck said it took fire crews about an hour to extricate them.