Fairfax County public schools said some of its buses across the area are late picking up students because of “significant mechanical problems” due to the freezing temperatures.

Officials warned that children should not stand outside for too long waiting for their buses.

In a statement on its Web site, the schools system said “some of these buses will be late picking up students; some may be very late.”

Fairfax police officials warned that parents should prepare to make other arrangements for getting their kids to school because as many as 200 buses “will not start.”

The school system is opening Friday under a two-hour delay because of the weather.

Officials said mechanics, transportation supervisors and drivers are “working to the best of their ability to get the buses running on time.”

Over the past few days, more than 260 buses have had problems starting because of the weather, according to Jeff Platenberg, the Fairfax County assistant superintendent for facilities and transportation. He said some buses wouldn’t start at all and needed to be towed.

Fairfax public schools has 1,600 buses in entire fleet. Platenberg said that the buses experienced various problems due to the extremely cold temperatures, including batteries that had died, frozen fuel lines and cracked windows.

“The lower temps and wind chill caused brake lines and fuel lines to freeze up and batteries to quit that were close to their end of useful life,” Platenberg said.

Fairfax has no centralized bus depot, like Montgomery County, and instead parks buses at scores of locations spread out around the county. In the mornings, drivers arrive at their buses at least an hour ahead of time in inclement weather to ensure that their motors get running. Platenberg said the school system relies on roaming mechanics, whom they call “roadies,” to help drivers address concerns with faulty engines.

“Our folks begin so early,” Platenberg said, noting that they “do simply miraculous work in the most adverse conditions.”

Platenberg said that in single-digit temperatures, diesel fuel will congeal in the tank, which makes it difficult for the engine to turn over. To address this concern, Platenberg said that bus mechanics had been replacing fuel filters and using a different type of fuel to keep it liquid.

One Fairfax bus driver, who spoke on condition of anonymity to be candid, said that she’s had difficulty getting her bus started in the past. She also said that the buses tend to be drafty.

“So we look like sausages with all our clothes on,” to stay warm, she said.

She drives about 40 to 65 kids to elementary and middle schools around the county. She noted that the bus drivers are trained extensively to handle wintery conditions on the roads, but in recent days the roads were too treacherous.

“The ice is scary, as are all the other folks on the road, but we are well trained,” she said.