The nation’s top rail safety inspector warned the railway company whose train destroyed the center of a Quebec town last month to cease using one-man crews on its trains, officials said Thursday.

Federal Railroad Administration administrator Joseph Szabo challenged but did not order Montreal, Maine and Atlantic Railway owner Ed Burkhardt to start using two-man crew operations in the U.S.

However, Canadian authorities ordered Montreal, Maine and Atlantic Railway to use two-man crews in Canada for all hazardous materials transports in response to the July 6 Lac-Megantic disaster, which killed 47 people.

“Because the risk associated with this accident also exists in the United States, it is my expectation that the same safety procedures will apply to your operations here,” Szabo wrote in a letter dated Wednesday. “I look forward to your written response confirming the use of two-man crews in the United States.”

Burkhardt did not immediately respond to a message left at his office in Chicago.

A Federal Railroad Administration official said that his agency could issue an emergency order requiring Montreal, Maine and Atlantic Railway to use two-man crews.