Day-old Victoria is back with her family this morning, thanks to four friends who went hunting for the baby after they saw a Facebook alert about her abduction last night from a hospital in Trois-Rivières, Que.

In a Facebook post also thanking the three women and one man for their help, Victoria's mother, Mélissa McMahon, on Tuesday expressed the family's horror of having the newborn taken from the maternity ward at the Sainte-Marie pavillion of the Centre hospitalier régional de Trois-Rivières (CHRTR) the night before.

"Yesterday we experienced the worst time of our lives. It was a feeling that nobody should have to live through. The helplessness in this situation was difficult to accept," wrote McMahon.

Quebec provincial police said that just before 7 p.m. ET Monday, a woman dressed as a nurse showed up at the hospital and entered the maternity ward.

Police said the woman took the baby from the mother, and left the room with the newborn wrapped in a blue blanket.

“She walked calmly down the hall, wearing a nurse's uniform. No one asked any questions about who she was,” a hospital employee told Radio-Canada.

Amber Alert

Police issued an Amber Alert around 7 p.m., looking for a red Toyota Yaris hatchback with a "Bébé à bord" ("Baby on Board") sticker.

Sgt. Martine Asselin with provincial police says many people were contacting police with tips after the Amber Alert went out.

Four young adults say they saw the Amber Alert on Facebook, and later recognized a woman fitting the suspect's description. (Mathieu Papillon/Radio-Canada)

"The media really helped us put out the picture and the description fast. We could see on the TV, on the media, on Facebook, everything we needed and very fast... the public was able to call us and give us information," said Asselin.

The baby was found three hours later after the four young adults learned of the abduction through Facebook. Police had shared a photo on social networks of the woman police were seeking.

The four say they went looking for the vehicle of the woman at the centre of the hunt, and found one that fit the description — then called police.

Baby Victoria was abducted from a Trois-Rivières, Que., hospital Monday night but found three hours later thanks to an Amber Alert spotted on Facebook. (Twitter)

“We saw [the alert] on Facebook, and decided to go looking for red cars, and we saw the woman. We recognized her,” said 20-year-old Mélizanne Bergeron​.

21-year-old suspect arrested

Police say they arrested a 21-year-old woman at her home.

They found baby Victoria, and returned her to hospital.

On Tuesday, Victoria was taken home to her family.

McMahon said in her Facebook post that it was social media that helped save the baby:

"Thousands of people shared the photo of the woman on social networks," McMahon wrote. "Know that this is what has saved our little Victoria. Each click, each share made ​​the difference. Four wonderful people, who we had the chance to meet, identified the woman through Facebook."

The 21-year-old woman picked up by police is in hospital for a psychiatric evaluation, they say. She may appear in court later Tuesday.

Asselin said it is not yet known if there was any previous connection between the baby's mother and the suspect.

Security protocols

The head of health services in the region says the hospital is co-operating with the police investigation and will also conduct its own internal review.

Health Minister Gaétan Barrette says he has sent letters to all Quebec hospitals with obstetrics units, asking them to review security protocols.