As three Santa Fe locomotives roared past, the children - ages 7, 8 and 10 - excitedly pulled an imaginary overhead whistle in an apparently successful attempt to get the engineer to blow the train's horn. They then counted cars by waving their fingers at each one.

"This is the funnest place," Raul Gonzales said. "It's close to the tracks and there's rocks to throw."

"Trains," the largest circulated magazine aimed at people who never outgrew the fun of watching trains, rates the Cajon Pass as the second best place in the United States where so-called "railfans" can gather and gawk at the estimated 100 trains that rumble through the pass daily.

"It's like a theme park for railfans," said Kevin Keefe, associate publisher of the Milwaukee-based magazine. "Trains, and lots of them."

Keefe said the No. 1 spot also is in California: the Tehachapi Loop near Bakersfield.

That's where railfans gather and cheer at trains that sometimes are long enough to cross head-over-tail as they climb or descend a 360-degree turn through the Tehachapi Mountains.

The magazine estimates that there are about 175,000 railfans in the United States.

Keefe said the Cajon Pass and is especially interesting because its steep grade means trains brake to slow as they descend into the Los Angeles basin.

He said the task takes a talented engineer who can control trains weighing up to 10,000 tons.

"Going up is a lot easier than coming down," Keefe said. "It's about managing gravity as you try to get from one altitude to another."

Keefe said the Cajon Pass is filled with places to park and watch. He said he likes the Gonzales children's viewpoint, which is on the shoulder of Cajon Boulevard just below the Cleghorn Fire Road exit off Interstate 215.

Another spot he likes is at Summit on Highway 138 between Interstate 215 and Silverwood Lake. He said that's where trains crest the San Bernardino Mountains.

Since 9-11, Keefe said, authorities are increasingly questioning railfans about taking pictures of trains and telling them to move along.

"I don't want to minimize the terrorist threat, but railfans with cameras shouldn't be the targets of police," Keefe said. "These guys are practicing a hobby."

Keefe said these incidents occur more often on the East Coast then the West Coast.

"Even if a cop is completely wrong, 99 percent of enthusiasts aren't going to argue," Keefe said. "Everybody I know is shrugging their shoulders and moving on."

Keefe warns that people should watch trains from public property. He said trains can sneak up on people playing on tracks.

"Trains are quiet when they come downhill," Keefe said. "They're not running on full throttle."

Statistics from the Federal Railroad Administration show 12 people, identified as "trespassers," were killed or injured on or near railroad tracks in San Bernardino County in 2003. Riverside County had 20 people killed or injured.

Through May, 2004 statistics show six people in San Bernardino County and two in Riverside County were killed or injured.

Lena Kent, a spokeswoman for the Burlington Northern and Santa Fe, said two of the three lines in the Cajon Pass belong to her railroad, the other belonging to Union Pacific. She said the Pass is a major artery for trains heading from the ports of Los Angeles and Long Beach to destinations east, including Chicago and New York.

"I've had requests from all over the world from people wanting information on watching trains in the Pass," Kent said.

Kent said she doesn't give recommendations. She suggests people resist the urge to cross onto the tracks, which are private property. She said railroad detectives patrol the area and have arrested people for offenses involving vandalism and trespassing.

"We appreciate the enthusiasm rail fans have," Kent said. "However, we want people to know trains can't stop quickly."

Eighty-two year old Chard Walker of Hesperia misses the steam engines that roamed the Cajon Pass when he started as a telegraph operator for the railroads in 1947.

"The diesels - they don't turn me on," Walker said. "They've lost the interest and romance the steam engines had."

Walker, who retired in 1983, has written three books about railroading in Cajon Pass. He said railfans have always dotted the area.

"In the earlier years, there weren't that many people up there taking pictures," he said.

People have been watching trains at the newly renovated San Bernardino depot since it opened in June, said Cheryl Donahue, a spokeswoman for San Bernardino Associated Governments, which occupies its second floor.

Donahue said nearly 3,000 people gathered on June 13 to see the 77-year-old steam engine 3751 make a stop at a depot built in 1918.

"We have folks everyday," she said. "I see handfuls of them standing next to the tracks."

They don't yet have a place to sit. Donahue said a coffee shop could be coming soon.

The Gonzales children never considering sitting while counting cars in the Cajon Pass.

Their grandmother, Lorraine Halverson, said she gave the children an option about the route to her house in Hesperia.

"I asked the kids, 'Freeway or alternate route?'" she said. "They wanted trains today."