A CSX Corp coal train derailed early on Thursday in Maryland, the second accident involving a company train within 24 hours.

It was the latest in a string of mishaps this week for one of the largest U.S. railroads.

Shares of the company fell 1.3 percent to $27.86 on the New York Stock Exchange.

Three locomotives and 10 cars on a train with thousands of tons of coal rolled off the tracks near Lanham, Maryland, but did not overturn, a local television station reported.

About 12 hours earlier, some 15 train cars carrying volatile Bakken crude from North Dakota derailed in downtown Lynchburg, Virginia. Several cars erupted in flames.

Earlier this week, a fire also broke out at a CSX tunnel used by coal trains in Pike County, Kentucky.

Smoke from the fire shut a nearby high school and prompted the U.S. Environmental Protection Agency to monitor air quality in the area, local TV station WSAZ reported.

The causes of the accidents were not known. In January, CSX had a derailment and near-miss in central Philadelphia over the Schuylkill River.

The company, which reported first-quarter profit of $398 million in April, was not available to comment on the incidents in Maryland and Kentucky.

In Virginia, CSX said it was cooperating with the National Transportation Safety Board and cleaning up the accident site. State emergency managers estimated a total of 30,000 gallons (831 barrels) of crude oil leaked into the James River, creating a sheen up to 9 miles long, officials said.

The Virginia crash was the sixth fiery derailment in North America since a runaway train in Lac-Megantic, Quebec, derailed and exploded, killing 47 people last July.

At least three of the crashes involved oil from the Bakken, which is much lighter and more flammable than most other varieties.

Regulators have put crude-by-rail transport under review for safety concerns as booming onshore oil production outpaces new pipeline construction. (Reporting by Terry Wade; Editing by Jeffrey Benkoe)