BORDULAC, N.D. (AP) — All of the rail cars that contained hazardous materials have been removed from the site of a derailment in North Dakota, and all hotspots from the resulting fire have been extinguished, an official with CPKC said Monday.

Railroad spokesman Patrick Waldron said in an email that track repairs were completed early Monday, and rail traffic resumed following track safety inspections.

No one was injured in the pre-dawn Friday derailment, which knocked 29 CPKC train cars off the tracks in a marshy area surrounded by farmland about 140 miles (225 kilometers) northwest of Fargo, officials said.

The train was carrying anhydrous ammonia and other hazardous materials. Officials on Sunday briefly issued a shelter-in-place notice for area residents after air monitors detected low levels of anhydrous ammonia, said Andrew Kirking, emergency management coordinator for Stutsman and Foster counties in east-central North Dakota.

No injuries from the leak were reported, and the notice was lifted later Sunday when air monitoring levels returned to zero, Kirking said.

Exposure to high concentrations of ammonia in the air can cause burning of the eyes, nose, throat and respiratory tract, and can result in blindness, lung damage or death, health officials say. Exposure to lower amounts can result in coughing and irritation of the nose and throat.

The National Transportation Safety Board and Federal Railroad Administration is investigating the cause of the derailment.