RENO, Nev. (AP) _ A backhoe ruptured a 4-inch gas main today, making at least 27 people ill and forcing a several square blocks of downtown to be evacuated.

The natural gas leak was capped in about 30 minutes, but the area around the site remained cordoned off as fire crews checked buildings to ventilate any dangerous pockets of gas.

The Circus Circus Hotel Casino was among the buildings emptied, and workers at the $350 million Silver Legacy Resort under construction across the street also were forced to leave.

Reno Police Lt. Ken Bunker said the gas break occurred around 9 a.m.

``I'm standing a block away and we can clearly hear the releasing high pressure of this natural gas line,'' Bunker said from the scene as the evacuation was under way.

Becky Swanson, community relations director at Saint Mary's Regional Medical Center, said 17 people sought treatment for nausea, lightheadedness and eye irritation. Of those, four were admitted.

``There are folks walking in all the time,'' Ms. Swanson said. The hospital is about a block from the site of the leak.

Ten others were taken to Washoe Medical Center across town, according to hospital spokeswoman Jane Tors. They were being evaluated in the emergency room and it was not yet known if any would be admitted, she said.