Three people snatched a small shark from a pool at the San Antonio Aquarium and smuggled it out in a baby carriage over the weekend, the aquarium said Monday.

One suspect is in custody and "the shark is alive and well and on its way back to the aquarium," Jenny Spellman, the aquarium's general manager, told NBC News on Monday night.

Leon Valley Police Chief Joseph Salvaggio said officers initially refused to believe that the 911 call that came in Saturday was real. But "they finally convinced me that it was true somebody had walked in and stole a shark out of a aquarium," he told NBC affiliate WOAI of San Antonio.

Spellman said her reaction was "just absolute shock."

"I couldn't believe that somebody would do something like that," she said.

Security video released Monday shows the sharknappers strolling through the aquarium's hallway pushing the baby carriage along on Saturday before they drove off with the 16-inch shark in a red pickup truck.

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The aquarium said the thieves brought their own net with them to snag the shark from an interactive "touch pool" at the tide pool exhibit while an attendant was assisting other visitors.

They then ducked into a filter room and emptied out a bleach bucket, into which they deposited the shark, the aquarium said. They used the bucket to transfer the shark into the stroller and "hurried up the stairs and out to the parking lot," it said.

The aquarium said managers raced to the parking lot and caught up with the suspects — who denied access to both the vehicle and the stroller.

Salvaggio told reporters at the aquarium Monday night that police tracked the vehicle down and found a house close to that vehicle. They were able to recover the shark and get confessions from two of the suspects, he said.

He said it was obvious that the man who stole the shark had knowledge of how to care for that type of animal.

"When we got into the garage and into the house, it looked like almost a mock-up of here," he said, referring to the aquarium. "He had a lot of different marine animals in the home, very much knew what he was doing."

Salvaggio said the aquarium was lucky that it was dealing with someone who knew how to care for sharks.

"Luckily for the shark and for the aquarium here we were able to get that animal back into one piece," he said.

"We don't think he was planning on selling it. He didn't say that, but from looking at the other animals there, more than likely it was something that he wanted," he said. "He had had one of these in the past, don't know, I think the animal had died sometime in the past."

Jamie Shank, the aquarium’s assistant director of husbandry, said the shark, who is named Miss Helen, is "a tough little horn shark."

"When this happened all the staff was very heartbroken simply because we did not think that she would even survive that in itself," she told reporters. "I'm really proud of her and I'm so overjoyed to have her back."

She added that Miss Helen will go into quarantine for an observation period to ensure that she is unharmed before being returned to the exhibit.

Three people believed to have stolen a shark at the San Antonio Aquarium on Saturday can be seen in a security video. The shark was smuggled out in the baby stroller at the bottom left, the aquarium said. San Antonio Aquarium

The horn shark is a small, slow-swimming member of the bullhead shark species, found mainly off the West Coast from California to the Gulf of California. They mostly eat mollusks, crustaceans, worms and sea anemones.

"We value the lives of all of our animals and take pride in the care that we are able to give them as well as the education that we are able to give to the general public about these treasured species," the aquarium said.