LAS VEGAS (AP) _ Two motorists jumped onto a slow-moving school bus and stopped it from careening down a busy freeway after its driver was overcome by fumes from spilled cleaning fluid.

The two men then pulled the driver out and administered CPR until an ambulance arrived Thursday morning. Nevada Highway Patrol Trooper Steve Harney described the two men as heroes.

The Clark County school bus was carrying no students and was northbound on Interstate 15 near Valley View when the driver, Amarilys Pascual, 34, was overcome, Harney said. The bus slammed against a concrete median and swerved to the right.

Paul Gallien and Dennis Rooswinkel, who were driving in their cars next to the bus, slowed down rush-hour traffic on the three-lane freeway as the bus began to swerve.

The two parked their cars on the highway shoulder, chased down the bus, forced their way through the closed doors and were able to halt the slow-moving vehicle, Harney said.

Pascual was taken to University Medical Center, where she was treated and released.

``They (Gallien and Rooswinkel) took their lives in their own hands,'' Harney said. ``Their quick action was very heroic. There was the real possibility of the bus crashing or hitting other vehicles.''

Harney estimated the bus was going about one to seven miles an hour at the time Gallien and Rooswinkel chased it down. The two men first assumed the driver had suffered a heart attack when she slumped over the steering wheel.

The fluid was in a can in the bus glove compartment and apparently tipped over, Harney said. The liquid was described as extremely flammable.

``We're told a lot of drivers carry the liquid to clean bus seats,'' Harney said.