Three women are under investigation in Germany for launching paper sky lanterns into the air to celebrate on New Year's Day after a fire ripped through a building at a zoo, killing dozens of animals.

Officials at the Krefeld Zoo, located near the Dutch border, said Wednesday on Facebook that their "worst fears have become reality" after the overnight blaze, which killed over 30 animals in total, including five orangutans, two gorillas, a chimpanzee and several monkeys, as well as fruit bats and birds.

"An unfathomable tragedy hit us shortly after midnight," the zoo said. "Our ape building burned down to the foundation."

GERMANY ZOO FIRE KILLS MORE THAN 30 ANIMALS, MAY HAVE BEEN SPARKED BY NEW YEAR'S EVE 'SKY LANTERNS

On Thursday, police said three local women – a mother and her two daughters, ages 30 to 60 – approached them on New Year's Day after authorities held a news conference about the blaze.

Criminal police chief Gerd Hoppmann said the women had ordered five sky lanterns on the Internet and told authorities that they had believed they were legal in Germany. He added that there was nothing in the product description showing that they were banned.

Hoppmann described the women as “completely normal people who seemed very sensible, very responsible" and said it was “very courageous” of them to come forward, saving authorities a tricky investigation. He added that they feared reprisals and authorities limited the details given about the suspects.

Several witnesses reported that they had seen the cylindrical paper lanterns with little fires inside flying in the night sky shortly after midnight Wednesday near the Krefeld zoo.

Sky lanterns, which are sometimes also called Chinese lanterns, are a sort of hot-air balloon made of paper. They have been used in Asia for celebratory events for centuries, but are illegal in Germany.

Hoppmann said Wednesday investigators found some used lanterns on the ground that hadn't burned entirely and had handwritten notes on them.

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The women are now being investigated on suspicion of negligent arson, according to prosecutor Jens Frobel. The offense can carry a prison sentence of up to five years.

The fire started in a corner of the ape house's roof in the first minutes of the new year and spread rapidly. Police and firefighters received the first emergency calls at 12:38 a.m.

The animals either burned to death or died from smoke inhalation, authorities said. Investigators believe that just one lantern started the blaze.

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The destroyed ape house lacked fire detectors and sprinklers, which weren't required when it was built in the 1970s, according to the Associated Press. The zoo said, however, that it had passed regular fire protection check a few months ago.

Investigators plan to carry out tests to help find out why the blaze spread so quickly, including examining the roof that was renovated a few years ago after a hail storm.

The Associated Press contributed to this report.