DENVER -- Police still don't know who left a dead infant girl just outside a Denver hospital Tuesday night.

A security guard at Presbyterian/St. Luke's Medical Center discovered the infant in a basket beside an emergency call box on the hospital's driveway, police said. The box, with the word "Help" on it, was near the corner of 19th Avenue and Franklin streets in Denver.

"The security guard came out, took the female baby back inside the hospital, and a short time later the baby was pronounced dead," said Denver Police Detective Sharon Hahn.

Hahn said the emergency call button was pushed by someone at the box, but no voice was heard. The security guard walked out and found the baby at 7:40 p.m.

Denver police said it was not known what the intentions were of the person or persons who left the baby, described as a white or Hispanic girl.

"We don't know if the child was possibly stillborn or died in the process," Hahn said.

A coroner will determine how the baby died and if she had died before she was abandoned on the hospital driveway. The newborn was no more than a couple of days old, 7NEWS reported.

An autopsy, conducted Wednesday, will also attempt to further identify the child. Police said it could be two weeks before autopsy results are finalized.

A hospital spokeswoman said she is concerned about the welfare of the mother, who may need medical attention after giving birth.

"We wish this baby could have had medical help at the time of birth and we're also concerned about the mom. We're hoping that if she is in need of medical care that she is seeking that at this time," said BJ Gilmore, the chief nursing officer.

Police said they are not conducting a homicide investigation but a "death investigation."

There are surveillance cameras outside the hospital, but officials don't know yet if it was pointing in the direction of the call box or if it had captured video of the person who left the baby.

In 2000, the Colorado General Assembly passed a Safe Haven law which allows a parent to relinquish control of a newborn baby to a fire station or hospital within 72 hours without fear of criminal prosecution.

"There is no reason to just leave a baby and run because you can hand it over safely. No one is going to ask you questions," said Linda Prudhomme with Colorado Safe Haven for Newborns.

However, under the Safe Haven law the baby must be unharmed and the person must personally hand over the newborn to another person, face-to-face.

"Giving over a baby face-to-face to someone at a fire station or at a hospital allows you to ensure the safety of the baby but the process is still anonymous. You give the baby face-to-face, you give the baby safely, but you do not have to give your name," Prudhomme said. "If that baby had been healthy and had been handed over to personnel at that hospital, that person could have walked away and not had any fear of prosecution."

Police say this is the time to help educate people about the Safe Haven law to protect mothers and newborns in the future.

"All of us at Presbyterian/St. Luke's Medical Center are shaken and saddened by this tragic event. Hospitals are designated 'Safe Havens' allowing a mother to leave her newborn inside the Emergency Department with no questions asked. The Colorado law was established to try to protect infants. At Presbyterian/St. Luke's Medical Center we are ready and able to care for babies such as this. We want to encourage anyone in this type of situation to bring the baby to a Safe Haven location so we can care for it," Gilmore said.

Since the law was enacted in 2000, 15 children have been relinquished at hospitals and fire stations, Prudhomme said. But the nonprofit also said for those 15 babies saved, another 15 have been abandoned.

For information on the law, go to ColoradoSafeHaven.org or call the Colorado Safe Haven 24-hour toll-free hotline at 866-694-2229 (866-694-BABY).

A brown teddy bear, small balloons and a card now sits below the emergency call box.

"I'm so sorry you didn't get a chance. I wish you could have been saved," the note reads.

Police have no leads in the case. No one has called in with information all day Wednesday. Investigators are hoping someone in the public will point them to the mother. Anyone with information is urged to call Crime Stoppers at 720-913-STOP (7867).