North Dakota officials were calling for answers Friday on how another train derailed near the town of Casselton, just down the track from the scene of a fiery wreck involving a crude oil train less than a year ago. It was the fifth derailment in the area in 10 years.

The latest incident involved an empty crude oil train colliding with a derailed train carrying various products on Thursday evening. It shocked the small prairie town and others down the line with concerns about the safety of increasing shipments of crude from the state's western oil boom.

The community is no longer willing to accept that so many derailments are "coincidence" or the "Bermuda Triangle of the railroad," said Cass County Sheriff Paul Laney, who demanded deeper investigation into what might be causing the problems.

Government leaders had called for heightened safety along the line after a crash Dec. 30, about a half-mile down the track, produced explosions, a huge fire and temporary evacuation of much of the town of 2,500 people. No one was hurt in that incident, which involved a westbound soybean train derailing and an eastbound oil train crashing into it.

BNSF railway officials said in a statement that a train carrying lumber and other products derailed about 5:30 p.m. Thursday, striking the passing empty oil train, which was traveling west.

The track had been visually inspected earlier in the day and had been regularly inspected before that under federal standards, according to the statement. It said the company would "undertake a broad-based review of the infrastructure" in the area.

The derailment Thursday affected 21 cars of an eastbound train carrying lumber and paper and 12 cars of a westbound train carrying empty oil tankers, which overturned on the grounds of an ethanol plant.

Leaders in the town about 20 miles west of Fargo said they were relieved that no one was hurt in the incident, which happened near an ethanol plant.

"It doesn't increase our confidence in the railroad any," Casselton Mayor Lee Anderson said. "I was encouraged to hear that someone from the BNSF said it would be a really good idea to study the tracks and the soil and the subsoils and everything under Casselton, because they feel like we do, that there's something going on out here that's not being addressed."

'We dodged a bullet'

Laney said he couldn't believe it when, shortly after arriving home Thursday, he got a call saying there had been another train derailment near Casselton.

"We dodged a bullet, we got so lucky that those oil cars were empty, because it overturned right on the property of the ethanol plant and that could have been disastrous," he said.

While BNSF officials have been open, transparent and "amazing to work with" on a response level, Laney said, he feels the community deserves more research into what's happening there.

"We … I think, have been very patient, and we deserve some answers and we deserve some in-depth investment and investigation into that stretch of track to determine why this is happening," Laney said. "That's what I've been demanding."

The derailment also prompted statements from the state's governor and two U.S. senators, among others.

Sen. Heidi Heitkamp said the state was lucky that the crude oil train was empty and nobody was hurt.

"But we can't rely on luck," she said. "We need to make sure everyone is doing everything possible to prevent future derailments."

Sen. John Hoeven said such accidents underscore the need for more pipelines.

More than 30 cars were affected in the Thursday incident, including a dozen of the empty tank cars, which were newer and stronger — the newest cars available, according to the company.

The railway's visual inspection of the track Thursday was part of its ongoing inspection program, which requires inspections there at least four times a week, according to BNSF spokeswoman Amy McBeth. "BNSF and the industry agreed to additional inspections on crude oil routes earlier this year," she said in an e-mail.

Early this year, federal railroad administrator Joseph Szabo said in a letter to a North Dakota senator that his agency had an ongoing investigation and safety assessment of the BNSF rail line in Cass County. He cited two track-related derailments, including a misalignment near Casselton in 2005 and a broken rail near Page, N.D., in 2008. Others were equipment-related.

BNSF responded then that derailments on mainlines hit record lows last year and that busy routes are inspected twice as frequently as the Federal Railroad Administration requires.

The Associated Press and staff writer David Shaffer contributed to this report. @pamlouwagie • 612-673-7102