At least three people, including two high school students, were killed and several others were missing after an avalanche hit a school group in the French Alps Wednesday, according to officials there.

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Posted by Massi Miliano on Wednesday, January 13, 2016

The avalanche occurred after several groups of skiers dislodged a large snow slab, local councilor Gilles Strappazzon told BFM-TV.

The students who died were 14 and 16, Sky News reports. The third person killed was a Ukrainian man, officials said.

60 workers were engaged in a search-and-rescue operation with sniffer dogs and a helicopter to find anybody else who may have been missing as night fell.

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The Deux Alpes ski resort is roughly 20 miles southeast of Grenoble, where rescuers rushed some of the injured for medical treatment.

The avalanche occurred on a closed ski run, Venosc Mayor Pierre Balme told the Dauphine Libere newspaper. French media also report there had been an avalanche warning beforehand in the Deux Alpes region, which had experienced heavy snowfall for days.

The teacher survived, but four students were found in cardiac arrest, local media reported. The students had traveled to the Alps from the Lycee St. Exupery school in Lyon.

French President Francois Hollande sent his condolences.

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The Associated Press contributed to this report.