Two Natrona County School District buses suffered the same kind of mechanical malfunction within two hours of each other today.

No major injuries or damage were reported, but the district has grounded the these two and the two similar buses, district spokesman Kelly Eastes said.

"It was a bit of a shocker to us, too, I must say," Eastes said.

The first incident happened shortly before 7 a.m. on a bus taking 46 students from Crest Hill Elementary to Fort Laramie.

The driver noticed smoke, stopped the bus near Carriage Lane and Wyoming Boulevard, and notified dispatch of a possible fire, Eastes said.

Casper Fire-EMS, Casper Police and the Wyoming Medical Center responded to the scene.

Casper Fire spokesman Justin Smith said emergency crews found no fire, but a lot of steam caused by a leaking heater hose.

"There was a great deal of steam that appeared to be smoke," Smith said.

One student was taken to the Wyoming Medical Center for further observation, he said. Some personal items were contaminated by the fluid and bagged for return to student families for decontamination, he added.

Eastes said some students returned home to get cleaned up, and the school canceled the trip.

The other incident happened about an hour later, he said.

Four buses carrying Natrona County High School band members were traveling on Interstate 25 to Denver when a hose began leaking. The bus pulled off at Chugwater and the students were evacuated, Eastes said.

Those students were transferred to the other three buses and continued their trip. One student reported having some steam on his leg, but did not seek medical attention, Eastes said.

The district has 121 buses in its fleet, and 95 percent of them are manufactured by Blue Bird, he said.

Because of the coincidence of timing, the year make and model of buses, the district has pulled these two 2009 Blue Birds and the two others from that year pulled from its fleet, Eastes said.

The district and its mechanics are working with the Casper Fire Department and the manufacture to determine and resolve the problems, he said.